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Climate and Average Weather Year Round in Iwanai Japan

In Iwanai, the summers are comfortable, wet, and partly cloudy and the winters are freezing, snowy, windy, and overcast. Over the course of the year, the temperature typically varies from 20°F to 77°F and is rarely below 12°F or above 84°F.

Based on the tourism score, the best time of year to visit Iwanai for warm-weather activities is from early July to early September.

Climate in Iwanai

freezingvery coldcoldcoolcomfortablewarmcoolcoldvery coldJanFebMarAprMayJunJulAugSepOctNovDecNowNow64%64%14%14%overcastclearprecipitation: 5.1 inprecipitation: 5.1 in1.5 in1.5 inmuggy: 54%muggy: 54%0%0%drydrytourism score: 6.7tourism score: 6.70.00.0
Iwanai weather by month. Click on each chart for more information.

The warm season lasts for 3.2 months, from June 18 to September 24, with an average daily high temperature above 67°F. The hottest month of the year in Iwanai is August, with an average high of 76°F and low of 65°F.

The cold season lasts for 3.7 months, from November 30 to March 20, with an average daily high temperature below 39°F. The coldest month of the year in Iwanai is January, with an average low of 21°F and high of 30°F.

Average High and Low Temperature in Iwanai

Average High and Low Temperature in IwanaiwarmcoldcoldJanFebMarAprMayJunJulAugSepOctNovDec0°F0°F10°F10°F20°F20°F30°F30°F40°F40°F50°F50°F60°F60°F70°F70°F80°F80°F90°F90°F100°F100°FJan 2529°FJan 2529°FAug 777°FAug 777°F20°F20°F66°F66°FJun 1867°FJun 1867°FSep 2467°FSep 2467°FNov 3039°FNov 3039°FMar 2039°FMar 2039°F55°F55°F55°F55°F30°F30°F30°F30°FNowNow
The daily average high (red line) and low (blue line) temperature, with 25th to 75th and 10th to 90th percentile bands. The thin dotted lines are the corresponding average perceived temperatures.
AverageJanFebMarAprMayJunJulAugSepOctNovDec
High 30°F31°F38°F50°F60°F67°F73°F76°F70°F59°F45°F35°F
Temp. 26°F26°F33°F43°F52°F60°F67°F70°F64°F53°F41°F30°F
Low 21°F22°F29°F38°F47°F55°F62°F65°F58°F47°F36°F26°F

The figure below shows you a compact characterization of the entire year of hourly average temperatures. The horizontal axis is the day of the year, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.

Average Hourly Temperature in Iwanai

Average Hourly Temperature in IwanaiJanFebMarAprMayJunJulAugSepOctNovDec12 AM12 AM2 AM2 AM4 AM4 AM6 AM6 AM8 AM8 AM10 AM10 AM12 PM12 PM2 PM2 PM4 PM4 PM6 PM6 PM8 PM8 PM10 PM10 PM12 AM12 AMNowNowfreezingvery coldcoldcoldcoolcoolcomfortablevery coldwarmfreezing
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
The average hourly temperature, color coded into bands. The shaded overlays indicate night and civil twilight.

Port Colborne, Canada (6,019 miles away) is the far-away foreign place with temperatures most similar to Iwanai (view comparison).

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Compare Iwanai to another city:

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In Iwanai, the average percentage of the sky covered by clouds experiences significant seasonal variation over the course of the year.

The clearer part of the year in Iwanai begins around March 13 and lasts for 8.4 months, ending around November 25.

The clearest month of the year in Iwanai is October, during which on average the sky is clear, mostly clear, or partly cloudy 62% of the time.

The cloudier part of the year begins around November 25 and lasts for 3.6 months, ending around March 13.

The cloudiest month of the year in Iwanai is January, during which on average the sky is overcast or mostly cloudy 85% of the time.

Cloud Cover Categories in Iwanai

Cloud Cover Categories in IwanaiclearercloudiercloudierJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%Oct 1164%Oct 1164%Jan 1814%Jan 1814%Mar 1339%Mar 1339%Nov 2539%Nov 2539%NowNowclearmostly clearpartly cloudymostly cloudyovercast
0% clear 20% mostly clear 40% partly cloudy 60% mostly cloudy 80% overcast 100%
The percentage of time spent in each cloud cover band, categorized by the percentage of the sky covered by clouds.
FractionJanFebMarAprMayJunJulAugSepOctNovDec
Cloudier 85%79%60%53%56%52%51%51%44%38%54%74%
Clearer 15%21%40%47%44%48%49%49%56%62%46%26%

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Iwanai varies throughout the year.

The wetter season lasts 5.9 months, from August 25 to February 22, with a greater than 34% chance of a given day being a wet day. The month with the most wet days in Iwanai is December, with an average of 14.5 days with at least 0.04 inches of precipitation.

The drier season lasts 6.1 months, from February 22 to August 25. The month with the fewest wet days in Iwanai is June, with an average of 6.8 days with at least 0.04 inches of precipitation.

Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. Based on this categorization, the most common form of precipitation in Iwanai changes throughout the year.

Rain alone is the most common for 9.1 months, from March 8 to December 9. The month with the most days of rain alone in Iwanai is October, with an average of 12.3 days.

Snow alone is the most common for 2.9 months, from December 9 to March 8. The month with the most days of snow alone in Iwanai is January, with an average of 8.5 days.

Daily Chance of Precipitation in Iwanai

Daily Chance of Precipitation in IwanaisnowrainJanFebMarAprMayJunJulAugSepOctNovDec0%0%10%10%20%20%30%30%40%40%50%50%60%60%70%70%80%80%90%90%100%100%Dec 1348%Dec 1348%Mar 2820%Mar 2820%Aug 2534%Aug 2534%Feb 2234%Feb 2234%NowNowsnowrainmixed
The percentage of days in which various types of precipitation are observed, excluding trace quantities: rain alone, snow alone, and mixed (both rain and snow fell in the same day).
Days ofJanFebMarAprMayJunJulAugSepOctNovDec
Rain 2.0d2.1d3.7d6.8d7.9d6.8d8.3d9.9d10.6d12.3d10.8d4.7d
Mixed 2.2d1.7d1.4d0.2d0.0d0.0d0.0d0.0d0.0d0.1d1.6d3.5d
Snow 8.5d6.6d2.3d0.1d0.0d0.0d0.0d0.0d0.0d0.0d1.5d6.3d
Any 12.7d10.4d7.5d7.1d7.9d6.8d8.3d9.9d10.6d12.4d13.9d14.5d

To show variation within the months and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day of the year. Iwanai experiences extreme seasonal variation in monthly rainfall.

Rain falls throughout the year in Iwanai. The month with the most rain in Iwanai is August, with an average rainfall of 4.8 inches.

The month with the least rain in Iwanai is February, with an average rainfall of 0.7 inches.

Average Monthly Rainfall in Iwanai

Average Monthly Rainfall in IwanaiJanFebMarAprMayJunJulAugSepOctNovDec0 in0 in5 in5 in10 in10 in15 in15 inSep 15.1 inSep 15.1 inFeb 20.6 inFeb 20.6 inMay 32.3 inMay 32.3 inNowNow
The average rainfall (solid line) accumulated over the course of a sliding 31-day period centered on the day in question, with 25th to 75th and 10th to 90th percentile bands. The thin dotted line is the corresponding average snowfall.
JanFebMarAprMayJunJulAugSepOctNovDec
Rainfall 0.8″0.7″1.1″1.9″2.1″2.1″3.2″4.8″4.7″4.2″3.6″1.8″

Snowfall

As with rainfall, we consider the snowfall accumulated over a sliding 31-day period centered around each day of the year. Iwanai experiences extreme seasonal variation in monthly snowfall.

The snowy period of the year lasts for 5.2 months, from October 30 to April 4, with a sliding 31-day snowfall of at least 1.0 inches. The month with the most snow in Iwanai is January, with an average snowfall of 15.5 inches.

The snowless period of the year lasts for 6.8 months, from April 4 to October 30. The least snow falls around July 21, with an average total accumulation of 0.0 inches.

Average Monthly Snowfall in Iwanai

Average Monthly Snowfall in IwanaisnowsnowJanFebMarAprMayJunJulAugSepOctNovDec0 in0 in5 in5 in10 in10 in15 in15 in20 in20 in25 in25 in30 in30 inJan 316.4 inJan 316.4 inJul 210.0 inJul 210.0 inOct 301.0 inOct 301.0 inApr 41.0 inApr 41.0 in
The average snowfall (solid line) accumulated over the course of a sliding 31-day period centered on the day in question, with 25th to 75th and 10th to 90th percentile bands. The thin dotted line is the corresponding average rainfall.
JanFebMarAprMayJunJulAugSepOctNovDec
Snowfall 15.5″12.1″4.3″0.3″0.0″0.0″0.0″0.0″0.0″0.2″3.9″14.5″

The length of the day in Iwanai varies significantly over the course of the year. In 2024, the shortest day is December 21, with 9 hours, 0 minutes of daylight; the longest day is June 21, with 15 hours, 22 minutes of daylight.

Hours of Daylight and Twilight in Iwanai

Hours of Daylight and Twilight in IwanaiJanFebMarAprMayJunJulAugSepOctNovDec0 hr24 hr4 hr20 hr8 hr16 hr12 hr12 hr16 hr8 hr20 hr4 hr24 hr0 hr12 hr, 9 minMar 2012 hr, 9 minMar 2015 hr, 22 minJun 2115 hr, 22 minJun 2112 hr, 10 minSep 2212 hr, 10 minSep 229 hr, 0 minDec 219 hr, 0 minDec 21nightnightdayNowNow
The number of hours during which the Sun is visible (black line). From bottom (most yellow) to top (most gray), the color bands indicate: full daylight, twilight (civil, nautical, and astronomical), and full night.
Hours ofJanFebMarAprMayJunJulAugSepOctNovDec
Daylight 9.4h10.5h12.0h13.4h14.7h15.3h15.0h13.9h12.5h11.0h9.7h9.1h

The earliest sunrise is at 3:58 AM on June 15, and the latest sunrise is 3 hours, 11 minutes later at 7:09 AM on January 4. The earliest sunset is at 4:03 PM on December 8, and the latest sunset is 3 hours, 18 minutes later at 7:21 PM on June 26.

Daylight saving time (DST) is not observed in Iwanai during 2024.

Sunrise & Sunset with Twilight in Iwanai

Sunrise & Sunset with Twilight in IwanaiJanFebMarAprMayJunJulAugSepOctNovDec12 AM2 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PMJun 153:58 AMJun 153:58 AM7:21 PMJun 267:21 PMJun 26Dec 84:03 PMDec 84:03 PM7:09 AMJan 47:09 AMJan 4daynightnightnightnightSolarMidnightSolarMidnightSolarNoonSunriseSunsetNowNow
The solar day over the course of the year 2024. From bottom to top, the black lines are the previous solar midnight, sunrise, solar noon, sunset, and the next solar midnight. The day, twilights (civil, nautical, and astronomical), and night are indicated by the color bands from yellow to gray.

The figure below presents a compact representation of the sun's elevation (the angle of the sun above the horizon) and azimuth (its compass bearing) for every hour of every day in the reporting period. The horizontal axis is the day of the year and the vertical axis is the hour of the day. For a given day and hour of that day, the background color indicates the azimuth of the sun at that moment. The black isolines are contours of constant solar elevation.

Solar Elevation and Azimuth in Iwanai

Solar Elevation and Azimuth in IwanaiJanFebMarAprMayJunJulAugSepOctNovDec12 AM12 AM2 AM2 AM4 AM4 AM6 AM6 AM8 AM8 AM10 AM10 AM12 PM12 PM2 PM2 PM4 PM4 PM6 PM6 PM8 PM8 PM10 PM10 PM12 AM12 AM0000101010102020202030303040405060600000101010102020202030303040405050602470NowNow
northeastsouthwest
Solar elevation and azimuth over the course of the year 2024. The black lines are lines of constant solar elevation (the angle of the sun above the horizon, in degrees). The background color fills indicate the azimuth (the compass bearing) of the sun. The lightly tinted areas at the boundaries of the cardinal compass points indicate the implied intermediate directions (northeast, southeast, southwest, and northwest).

The figure below presents a compact representation of key lunar data for 2024. The horizontal axis is the day, the vertical axis is the hour of the day, and the colored areas indicate when the moon is above the horizon. The vertical gray bars (new Moons) and blue bars (full Moons) indicate key Moon phases.

Moon Rise, Set & Phases in Iwanai

The time in which the moon is above the horizon (light blue area), with new moons (dark gray lines) and full moons (blue lines) indicated. The shaded overlays indicate night and civil twilight.

We base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night.

Iwanai experiences extreme seasonal variation in the perceived humidity.

The muggier period of the year lasts for 2.2 months, from July 8 to September 14, during which time the comfort level is muggy, oppressive, or miserable at least 13% of the time. The month with the most muggy days in Iwanai is August, with 14.3 days that are muggy or worse.

The least muggy day of the year is March 15, when muggy conditions are essentially unheard of.

Humidity Comfort Levels in Iwanai

Humidity Comfort Levels in IwanaimuggyJanFebMarAprMayJunJulAugSepOctNovDec0%0%10%10%20%20%30%30%40%40%50%50%60%60%70%70%80%80%90%90%100%100%Mar 150%Mar 150%Aug 654%Aug 654%Jul 813%Jul 813%Sep 1413%Sep 1413%muggymuggydrydryhumidhumidoppressiveoppressivecomfortablecomfortable
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
The percentage of time spent at various humidity comfort levels, categorized by dew point.
JanFebMarAprMayJunJulAugSepOctNovDec
Muggy days 0.0d0.0d0.0d0.0d0.0d0.4d8.2d14.3d3.8d0.1d0.0d0.0d

This section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages.

The average hourly wind speed in Iwanai experiences significant seasonal variation over the course of the year.

The windier part of the year lasts for 6.4 months, from October 11 to April 24, with average wind speeds of more than 8.9 miles per hour. The windiest month of the year in Iwanai is February, with an average hourly wind speed of 12.1 miles per hour.

The calmer time of year lasts for 5.6 months, from April 24 to October 11. The calmest month of the year in Iwanai is July, with an average hourly wind speed of 5.6 miles per hour.

Average Wind Speed in Iwanai

Average Wind Speed in IwanaiwindywindyJanFebMarAprMayJunJulAugSepOctNovDec0 mph0 mph2 mph2 mph4 mph4 mph6 mph6 mph8 mph8 mph10 mph10 mph12 mph12 mph14 mph14 mph16 mph16 mph18 mph18 mphFeb 812.3 mphFeb 812.3 mphJul 55.5 mphJul 55.5 mphOct 118.9 mphOct 118.9 mphApr 248.9 mphApr 248.9 mphNowNow
The average of mean hourly wind speeds (dark gray line), with 25th to 75th and 10th to 90th percentile bands.
JanFebMarAprMayJunJulAugSepOctNovDec
Wind Speed (mph) 12.012.111.19.37.76.05.66.17.39.210.511.5

The predominant average hourly wind direction in Iwanai varies throughout the year.

The wind is most often from the south for 5.1 months, from April 11 to September 14, with a peak percentage of 51% on July 27. The wind is most often from the west for 6.9 months, from September 14 to April 11, with a peak percentage of 64% on January 1.

Wind Direction in Iwanai

Wind Direction in IwanaiWSWJanFebMarAprMayJunJulAugSepOctNovDec0%100%20%80%40%60%60%40%80%20%100%0%NowNowwestsouthnortheast
northeastsouthwest
The percentage of hours in which the mean wind direction is from each of the four cardinal wind directions, excluding hours in which the mean wind speed is less than 1.0 mph. The lightly tinted areas at the boundaries are the percentage of hours spent in the implied intermediate directions (northeast, southeast, southwest, and northwest).

Iwanai is located near a large body of water (e.g., ocean, sea, or large lake). This section reports on the wide-area average surface temperature of that water.

The average water temperature experiences significant seasonal variation over the course of the year.

The time of year with warmer water lasts for 2.7 months, from July 16 to October 5, with an average temperature above 65°F. The month of the year in Iwanai with the warmest water is August, with an average temperature of 70°F.

The time of year with cooler water lasts for 4.6 months, from December 17 to May 4, with an average temperature below 47°F. The month of the year in Iwanai with the coolest water is February, with an average temperature of 42°F.

Average Water Temperature in Iwanai

Average Water Temperature in IwanaiwarmcoolJanFebMarAprMayJunJulAugSepOctNovDec35°F35°F40°F40°F45°F45°F50°F50°F55°F55°F60°F60°F65°F65°F70°F70°F75°F75°F80°F80°FAug 2271°FAug 2271°F42°FFeb 2442°FFeb 24Jul 1665°FJul 1665°FOct 565°FOct 565°FDec 1747°FDec 1747°FMay 447°FMay 447°FNowNow
The daily average water temperature (purple line), with 25th to 75th and 10th to 90th percentile bands.
WaterJanFebMarAprMayJunJulAugSepOctNovDec
Temperature 44°F42°F42°F45°F50°F58°F65°F70°F69°F62°F55°F48°F

To characterize how pleasant the weather is in Iwanai throughout the year, we compute two travel scores.

The tourism score favors clear, rainless days with perceived temperatures between 65°F and 80°F. Based on this score, the best time of year to visit Iwanai for general outdoor tourist activities is from early July to early September, with a peak score in the second week of August.

Tourism Score in Iwanai

Tourism Score in Iwanaibest timeJanFebMarAprMayJunJulAugSepOctNovDec002244668810106.76.70.00.0NowNowtemperaturetemperaturecloudscloudsprecipitationprecipitationtourism score
The tourism score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).

The beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F. Based on this score, the best time of year to visit Iwanai for hot-weather activities is from late July to late August, with a peak score in the first week of August.

Beach/Pool Score in Iwanai

Beach/Pool Score in IwanaiJanFebMarAprMayJunJulAugSepOctNovDec002244668810103.73.70.00.0NowNowtemperaturetemperature cloudscloudsprecipitationprecipitationbeach/pool score
The beach/pool score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).

Methodology

For each hour between 8:00 AM and 9:00 PM of each day in the analysis period (1980 to 2016), independent scores are computed for perceived temperature, cloud cover, and total precipitation. Those scores are combined into a single hourly composite score, which is then aggregated into days, averaged over all the years in the analysis period, and smoothed.

Our cloud cover score is 10 for fully clear skies, falling linearly to 9 for mostly clear skies, and to 1 for fully overcast skies.

Our precipitation score, which is based on the three-hour precipitation centered on the hour in question, is 10 for no precipitation, falling linearly to 9 for trace precipitation, and to 0 for 0.04 inches of precipitation or more.

Our tourism temperature score is 0 for perceived temperatures below 50°F, rising linearly to 9 for 65°F, to 10 for 75°F, falling linearly to 9 for 80°F, and to 1 for 90°F or hotter.

Our beach/pool temperature score is 0 for perceived temperatures below 65°F, rising linearly to 9 for 75°F, to 10 for 82°F, falling linearly to 9 for 90°F, and to 1 for 100°F or hotter.

Definitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere).

The growing season in Iwanai typically lasts for 7.1 months (217 days), from around April 9 to around November 12, rarely starting before March 25 or after April 24, and rarely ending before October 28 or after November 27.

Time Spent in Various Temperature Bands and the Growing Season in Iwanai

Time Spent in Various Temperature Bands and the Growing Season in Iwanaigrowing seasonJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%50%Apr 950%Apr 950%Nov 1250%Nov 1290%Apr 2490%Apr 2490%Oct 2890%Oct 2810%Mar 2510%Mar 2510%Nov 2710%Nov 270%Dec 230%Dec 23Aug 2100%Aug 2100%freezingvery coldcoldcoolcomfortablewarmfrigid
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
The percentage of time spent in various temperature bands. The black line is the percentage chance that a given day is within the growing season.

Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F.

Based on growing degree days alone, the first spring blooms in Iwanai should appear around May 20, only rarely appearing before May 12 or after May 29.

Growing Degree Days in Iwanai

Growing Degree Days in IwanaiJanFebMarAprMayJunJulAugSepOctNovDec0°F0°F500°F500°F1,000°F1,000°F1,500°F1,500°F2,000°F2,000°FMay 2090°FMay 2090°FJul 28900°FJul 28900°FSep 131,800°FSep 131,800°FDec 312,164°FDec 312,164°F
The average growing degree days accumulated over the course of the year, with 25th to 75th and 10th to 90th percentile bands.

This section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation.

The average daily incident shortwave solar energy experiences extreme seasonal variation over the course of the year.

The brighter period of the year lasts for 4.0 months, from April 20 to August 21, with an average daily incident shortwave energy per square meter above 5.2 kWh. The brightest month of the year in Iwanai is June, with an average of 6.1 kWh.

The darker period of the year lasts for 3.4 months, from November 6 to February 16, with an average daily incident shortwave energy per square meter below 2.1 kWh. The darkest month of the year in Iwanai is December, with an average of 1.1 kWh.

Average Daily Incident Shortwave Solar Energy in Iwanai

Average Daily Incident Shortwave Solar Energy in IwanaibrightdarkdarkJanFebMarAprMayJunJulAugSepOctNovDec0 kWh0 kWh1 kWh1 kWh2 kWh2 kWh3 kWh3 kWh4 kWh4 kWh5 kWh5 kWh6 kWh6 kWh7 kWh7 kWh8 kWh8 kWh9 kWh9 kWhJun 106.2 kWhJun 106.2 kWhDec 281.1 kWhDec 281.1 kWhApr 205.2 kWhApr 205.2 kWhAug 215.2 kWhAug 215.2 kWhNov 62.1 kWhNov 62.1 kWhFeb 162.1 kWhFeb 162.1 kWhNowNow
The average daily shortwave solar energy reaching the ground per square meter (orange line), with 25th to 75th and 10th to 90th percentile bands.
JanFebMarAprMayJunJulAugSepOctNovDec
Solar Energy (kWh) 1.22.03.55.05.76.16.05.34.33.11.81.1

For the purposes of this report, the geographical coordinates of Iwanai are 42.974 deg latitude, 140.509 deg longitude, and 20 ft elevation.

The topography within 2 miles of Iwanai contains very significant variations in elevation, with a maximum elevation change of 1,007 feet and an average elevation above sea level of 126 feet. Within 10 miles contains very significant variations in elevation (3,980 feet). Within 50 miles also contains extreme variations in elevation (6,198 feet).

The area within 2 miles of Iwanai is covered by water (36%), trees (31%), cropland (16%), and grassland (12%), within 10 miles by trees (46%) and water (39%), and within 50 miles by water (64%) and trees (27%).

This report illustrates the typical weather in Iwanai, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.

Temperature and Dew Point

There are 2 weather stations near enough to contribute to our estimation of the temperature and dew point in Iwanai.

For each station, the records are corrected for the elevation difference between that station and Iwanai according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations.

The estimated value at Iwanai is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Iwanai and a given station.

The stations contributing to this reconstruction are:

  • Muroran (RJCY, 56%, 51 mi, southeast, 141 ft elevation change)
  • Chitose Air Base (RJCJ, 44%, 60 mi, east, 66 ft elevation change)

To get a sense of how much these sources agree with each other, you can view a comparison of Iwanai and the stations that contribute to our estimates of its temperature history and climate. Please note that each source's contribution is adjusted for elevation and the relative change present in the MERRA-2 data.

Other Data

All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Algorithms 2nd Edition , by Jean Meeus.

All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . This reanalysis combines a variety of wide-area measurements in a state-of-the-art global meteorological model to reconstruct the hourly history of weather throughout the world on a 50-kilometer grid.

Land Use data comes from the Global Land Cover SHARE database , published by the Food and Agriculture Organization of the United Nations.

Elevation data comes from the Shuttle Radar Topography Mission (SRTM) , published by NASA's Jet Propulsion Laboratory.

Names, locations, and time zones of places and some airports come from the GeoNames Geographical Database .

Time zones for airports and weather stations are provided by AskGeo.com .

Maps are © OpenStreetMap contributors.

Disclaimer

The information on this site is provided as is, without any assurances as to its accuracy or suitability for any purpose. Weather data is prone to errors, outages, and other defects. We assume no responsibility for any decisions made on the basis of the content presented on this site.

We draw particular cautious attention to our reliance on the MERRA-2 model-based reconstructions for a number of important data series. While having the tremendous advantages of temporal and spatial completeness, these reconstructions: (1) are based on computer models that may have model-based errors, (2) are coarsely sampled on a 50 km grid and are therefore unable to reconstruct the local variations of many microclimates, and (3) have particular difficulty with the weather in some coastal areas, especially small islands.

We further caution that our travel scores are only as good as the data that underpin them, that weather conditions at any given location and time are unpredictable and variable, and that the definition of the scores reflects a particular set of preferences that may not agree with those of any particular reader.

Please review our full terms contained on our Terms of Service page.