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Climate and Average Weather Year Round in Rock Falls Illinois, United States

In Rock Falls, the summers are long, warm, and wet; the winters are freezing, snowy, and windy; and it is partly cloudy year round. Over the course of the year, the temperature typically varies from 15°F to 84°F and is rarely below -6°F or above 92°F.

Based on the tourism score, the best time of year to visit Rock Falls for warm-weather activities is from early June to mid September.

Climate in Rock Falls

freezingvery coldcoldcoolwarmcoolcoldvery coldJanFebMarAprMayJunJulAugSepOctNovDecNowNow69%69%43%43%clearovercastprecipitation: 4.0 inprecipitation: 4.0 in1.0 in1.0 inmuggy: 42%muggy: 42%0%0%drydrytourism score: 6.5tourism score: 6.50.00.0
Rock Falls weather by month. Click on each chart for more information.

The warm season lasts for 4.1 months, from May 17 to September 20, with an average daily high temperature above 73°F. The hottest month of the year in Rock Falls is July, with an average high of 84°F and low of 64°F.

The cold season lasts for 3.1 months, from November 30 to March 1, with an average daily high temperature below 41°F. The coldest month of the year in Rock Falls is January, with an average low of 15°F and high of 30°F.

Average High and Low Temperature in Rock Falls

Average High and Low Temperature in Rock FallswarmcoldcoldJanFebMarAprMayJunJulAugSepOctNovDec-10°F-10°F0°F0°F10°F10°F20°F20°F30°F30°F40°F40°F50°F50°F60°F60°F70°F70°F80°F80°F90°F90°F100°F100°FJan 2230°FJan 2230°FJul 1884°FJul 1884°F15°F15°F64°F64°FMay 1773°FMay 1773°FSep 2073°FSep 2073°FNov 3041°FNov 3041°FMar 141°FMar 141°F52°F52°F51°F51°F26°F26°F24°F24°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°F34°F48°F62°F73°F81°F84°F82°F75°F63°F48°F34°F
Temp. 22°F26°F37°F50°F61°F70°F74°F71°F64°F52°F39°F27°F
Low 15°F19°F30°F40°F51°F60°F64°F61°F53°F42°F31°F20°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 Rock Falls

Average Hourly Temperature in Rock FallsJanFebMarAprMayJunJulAugSepOctNovDec12 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 AMNowNowfreezingfreezingvery coldvery coldcoldcoldcoolcomfortablecomfortablewarm
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.

Arzni, Armenia (6,091 miles away) and Tokmok, Kyrgyzstan (6,523 miles) are the far-away foreign places with temperatures most similar to Rock Falls (view comparison).

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In Rock Falls, 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 Rock Falls begins around June 10 and lasts for 4.5 months, ending around October 25.

The clearest month of the year in Rock Falls is August, during which on average the sky is clear, mostly clear, or partly cloudy 68% of the time.

The cloudier part of the year begins around October 25 and lasts for 7.5 months, ending around June 10.

The cloudiest month of the year in Rock Falls is December, during which on average the sky is overcast or mostly cloudy 56% of the time.

Cloud Cover Categories in Rock Falls

Cloud Cover Categories in Rock FallsclearercloudiercloudierJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%Aug 2569%Aug 2569%Dec 2843%Dec 2843%Jun 1056%Jun 1056%Oct 2556%Oct 2556%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 56%55%52%51%48%42%34%32%33%41%51%56%
Clearer 44%45%48%49%52%58%66%68%67%59%49%44%

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

The wetter season lasts 5.8 months, from March 30 to September 23, with a greater than 27% chance of a given day being a wet day. The month with the most wet days in Rock Falls is June, with an average of 11.8 days with at least 0.04 inches of precipitation.

The drier season lasts 6.2 months, from September 23 to March 30. The month with the fewest wet days in Rock Falls is January, with an average of 4.5 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 Rock Falls changes throughout the year.

Rain alone is the most common for 11 months, from February 8 to January 14. The month with the most days of rain alone in Rock Falls is June, with an average of 11.8 days.

Snow alone is the most common for 3.6 weeks, from January 14 to February 8. The month with the most days of snow alone in Rock Falls is January, with an average of 1.9 days.

Daily Chance of Precipitation in Rock Falls

Daily Chance of Precipitation in Rock FallssnowrainJanFebMarAprMayJunJulAugSepOctNovDec0%0%10%10%20%20%30%30%40%40%50%50%60%60%70%70%80%80%90%90%100%100%Jun 1340%Jun 1340%Jan 2913%Jan 2913%Mar 3027%Mar 3027%Sep 2327%Sep 2327%NowNowrainsnow
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 1.8d2.2d5.6d8.9d11.0d11.8d10.9d10.4d8.4d7.2d5.6d3.0d
Mixed 0.8d0.6d0.6d0.2d0.0d0.0d0.0d0.0d0.0d0.0d0.5d1.0d
Snow 1.9d1.6d0.6d0.0d0.0d0.0d0.0d0.0d0.0d0.0d0.3d1.5d
Any 4.5d4.5d6.8d9.1d11.0d11.8d10.9d10.4d8.4d7.2d6.3d5.5d

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. Rock Falls experiences significant seasonal variation in monthly rainfall.

Rain falls throughout the year in Rock Falls. The month with the most rain in Rock Falls is June, with an average rainfall of 4.0 inches.

The month with the least rain in Rock Falls is January, with an average rainfall of 0.6 inches.

Average Monthly Rainfall in Rock Falls

Average Monthly Rainfall in Rock FallsJanFebMarAprMayJunJulAugSepOctNovDec0 in0 in2 in2 in4 in4 in6 in6 in8 in8 inJun 134.0 inJun 134.0 inJan 210.6 inJan 210.6 inAug 153.6 inAug 153.6 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 0.6″0.9″1.7″2.9″3.5″4.0″3.3″3.6″3.0″2.5″2.0″1.2″

Snowfall

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

The snowy period of the year lasts for 4.4 months, from November 13 to March 25, with a sliding 31-day snowfall of at least 1.0 inches. The month with the most snow in Rock Falls is January, with an average snowfall of 4.0 inches.

The snowless period of the year lasts for 7.6 months, from March 25 to November 13. The least snow falls around July 14, with an average total accumulation of 0.0 inches.

Average Monthly Snowfall in Rock Falls

Average Monthly Snowfall in Rock FallssnowsnowJanFebMarAprMayJunJulAugSepOctNovDec0 in0 in2 in2 in4 in4 in6 in6 in8 in8 in10 in10 inJan 54.1 inJan 54.1 inJul 140.0 inJul 140.0 inNov 131.0 inNov 131.0 inMar 251.0 inMar 251.0 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 4.0″3.5″1.6″0.3″0.0″0.0″0.0″0.0″0.0″0.0″1.1″3.9″

The length of the day in Rock Falls varies significantly over the course of the year. In 2024, the shortest day is December 21, with 9 hours, 8 minutes of daylight; the longest day is June 20, with 15 hours, 13 minutes of daylight.

Hours of Daylight and Twilight in Rock Falls

Hours of Daylight and Twilight in Rock FallsJanFebMarAprMayJunJulAugSepOctNovDec0 hr24 hr4 hr20 hr8 hr16 hr12 hr12 hr16 hr8 hr20 hr4 hr24 hr0 hr12 hr, 8 minMar 1912 hr, 8 minMar 1915 hr, 13 minJun 2015 hr, 13 minJun 2012 hr, 11 minSep 2212 hr, 11 minSep 229 hr, 8 minDec 219 hr, 8 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 9.5h10.6h12.0h13.4h14.6h15.2h14.8h13.8h12.4h11.0h9.8h9.2h

The earliest sunrise is at 5:23 AM on June 14, and the latest sunrise is 2 hours, 10 minutes later at 7:32 AM on November 2. The earliest sunset is at 4:27 PM on December 8, and the latest sunset is 4 hours, 10 minutes later at 8:37 PM on June 26.

Daylight saving time (DST) is observed in Rock Falls during 2024, starting in the spring on March 10, lasting 7.8 months, and ending in the fall on November 3.

Sunrise & Sunset with Twilight and Daylight Saving Time in Rock Falls

Sunrise & Sunset with Twilight and Daylight Saving Time in Rock FallsJanFebMarAprMayJunJulAugSepOctNovDec12 AM2 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AMJun 145:23 AMJun 145:23 AM8:37 PMJun 268:37 PMJun 26Dec 84:27 PMDec 84:27 PM7:32 AMNov 27:32 AMNov 2Mar 10DSTMar 10DSTDSTNov 3DSTNov 3daynightnightnightnightSolarMidnightSolarMidnightSolarNoonSunriseSunsetNowNow
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 transitions to and from daylight saving time are indicated by the 'DST' labels.

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 Rock Falls

Solar Elevation and Azimuth in Rock FallsJanFebMarAprMayJunJulAugSepOctNovDec12 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 AM0001010101020202030303040405050606000010101020202020303040405050602572NowNow
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 Rock Falls

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.

Rock Falls experiences significant seasonal variation in the perceived humidity.

The muggier period of the year lasts for 3.5 months, from June 1 to September 15, during which time the comfort level is muggy, oppressive, or miserable at least 11% of the time. The month with the most muggy days in Rock Falls is July, with 12.2 days that are muggy or worse.

The month with the fewest muggy days in Rock Falls is January, with 0.0 days that are muggy or worse.

Humidity Comfort Levels in Rock Falls

Humidity Comfort Levels in Rock FallsmuggyJanFebMarAprMayJunJulAugSepOctNovDec0%0%10%10%20%20%30%30%40%40%50%50%60%60%70%70%80%80%90%90%100%100%Jan 290%Jan 290%Jul 2142%Jul 2142%Jun 111%Jun 111%Sep 1511%Sep 1511%NowNowmuggymuggycomfortablecomfortabledrydryhumidhumidoppressiveoppressive
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 0.0d0.0d0.0d0.0d1.3d6.2d12.2d10.4d3.5d0.3d0.0d0.0d

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 Rock Falls experiences significant seasonal variation over the course of the year.

The windier part of the year lasts for 7.7 months, from October 4 to May 25, with average wind speeds of more than 10.0 miles per hour. The windiest month of the year in Rock Falls is March, with an average hourly wind speed of 12.3 miles per hour.

The calmer time of year lasts for 4.3 months, from May 25 to October 4. The calmest month of the year in Rock Falls is August, with an average hourly wind speed of 7.7 miles per hour.

Average Wind Speed in Rock Falls

Average Wind Speed in Rock FallswindywindyJanFebMarAprMayJunJulAugSepOctNovDec0 mph0 mph2 mph2 mph4 mph4 mph6 mph6 mph8 mph8 mph10 mph10 mph12 mph12 mph14 mph14 mph16 mph16 mph18 mph18 mph20 mph20 mphMar 2212.5 mphMar 2212.5 mphAug 27.5 mphAug 27.5 mphOct 410.0 mphOct 410.0 mphMay 2510.0 mphMay 2510.0 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) 11.711.912.312.110.59.07.97.79.010.411.211.3

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

The wind is most often from the north for 1.6 months, from February 18 to April 6, with a peak percentage of 31% on March 7. The wind is most often from the south for 7.5 months, from April 6 to November 20, with a peak percentage of 38% on September 6. The wind is most often from the west for 2.9 months, from November 20 to February 18, with a peak percentage of 37% on January 1.

Wind Direction in Rock Falls

Wind Direction in Rock FallsWNSWJanFebMarAprMayJunJulAugSepOctNovDec0%100%20%80%40%60%60%40%80%20%100%0%NowNowwestsoutheastnorth
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).

To characterize how pleasant the weather is in Rock Falls 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 Rock Falls for general outdoor tourist activities is from early June to mid September, with a peak score in the first week of August.

Tourism Score in Rock Falls

Tourism Score in Rock Fallsbest timeJanFebMarAprMayJunJulAugSepOctNovDec002244668810106.56.50.00.0NowNowtemperaturetemperature cloudscloudsprecipitationprecipitationtourism 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 Rock Falls for hot-weather activities is from late June to mid August, with a peak score in the third week of July.

Beach/Pool Score in Rock Falls

Beach/Pool Score in Rock Fallsbest timeJanFebMarAprMayJunJulAugSepOctNovDec002244668810105.25.20.00.0NowNowtemperaturetemperature 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 Rock Falls typically lasts for 5.6 months (170 days), from around April 21 to around October 8, rarely starting before April 3 or after May 10, and rarely ending before September 21 or after October 25.

Time Spent in Various Temperature Bands and the Growing Season in Rock Falls

Time Spent in Various Temperature Bands and the Growing Season in Rock Fallsgrowing seasonJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%Apr 2150%Apr 2150%Oct 850%Oct 850%May 1090%May 1090%Sep 2190%Sep 2190%Apr 310%Apr 310%Oct 2510%Oct 2510%0%Feb 50%Feb 5Jul 22100%Jul 22100%NowNowfreezingvery coldcoolcomfortablewarmhotcold
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 Rock Falls should appear around April 11, only rarely appearing before March 29 or after April 25.

Growing Degree Days in Rock Falls

Growing Degree Days in Rock FallsJanFebMarAprMayJunJulAugSepOctNovDec0°F0°F500°F500°F1,000°F1,000°F1,500°F1,500°F2,000°F2,000°F2,500°F2,500°F3,000°F3,000°F3,500°F3,500°FApr 1189°FApr 1189°FJun 17900°FJun 17900°FJul 271,800°FJul 271,800°FDec 313,188°FDec 313,188°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 3.6 months, from May 3 to August 22, with an average daily incident shortwave energy per square meter above 5.9 kWh. The brightest month of the year in Rock Falls is July, with an average of 6.8 kWh.

The darker period of the year lasts for 3.3 months, from November 1 to February 10, with an average daily incident shortwave energy per square meter below 2.8 kWh. The darkest month of the year in Rock Falls is December, with an average of 1.8 kWh.

Average Daily Incident Shortwave Solar Energy in Rock Falls

Average Daily Incident Shortwave Solar Energy in Rock FallsbrightdarkdarkJanFebMarAprMayJunJulAugSepOctNovDec0 kWh0 kWh1 kWh1 kWh2 kWh2 kWh3 kWh3 kWh4 kWh4 kWh5 kWh5 kWh6 kWh6 kWh7 kWh7 kWh8 kWh8 kWh9 kWh9 kWhJun 307.0 kWhJun 307.0 kWhDec 201.7 kWhDec 201.7 kWhMay 35.9 kWhMay 35.9 kWhAug 225.9 kWhAug 225.9 kWhNov 12.8 kWhNov 12.8 kWhFeb 102.8 kWhFeb 102.8 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) 2.13.04.25.36.26.86.86.15.03.52.31.8

For the purposes of this report, the geographical coordinates of Rock Falls are 41.780 deg latitude, -89.689 deg longitude, and 646 ft elevation.

The topography within 2 miles of Rock Falls is essentially flat, with a maximum elevation change of 92 feet and an average elevation above sea level of 647 feet. Within 10 miles is essentially flat (256 feet). Within 50 miles contains only modest variations in elevation (814 feet).

The area within 2 miles of Rock Falls is covered by artificial surfaces (71%) and cropland (19%), within 10 miles by cropland (95%), and within 50 miles by cropland (89%).

This report illustrates the typical weather in Rock Falls, 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 5 weather stations near enough to contribute to our estimation of the temperature and dew point in Rock Falls.

For each station, the records are corrected for the elevation difference between that station and Rock Falls 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 Rock Falls is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Rock Falls and a given station.

The stations contributing to this reconstruction are:

To get a sense of how much these sources agree with each other, you can view a comparison of Rock Falls 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.