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Average Weather in Jämsä Finland

In Jämsä, the summers are comfortable and partly cloudy and the winters are long, freezing, snowy, and overcast. Over the course of the year, the temperature typically varies from 11°F to 71°F and is rarely below -12°F or above 80°F.

Based on the tourism score, the best time of year to visit Jämsä for warm-weather activities is from late June to mid August.

Climate Summary

freezingvery coldcoldcoolcomfortablecoolcoldvery coldfreezingJanFebMarAprMayJunJulAugSepOctNovDecNowNow56%56%16%16%overcastclearprecipitation: 3.0 inprecipitation: 3.0 in0.7 in0.7 inmuggy: 1%muggy: 1%0%0%drydrytourism score: 6.4tourism score: 6.40.00.0
Click on each chart for more information.

Temperature

The warm season lasts for 3.2 months, from May 26 to September 1, with an average daily high temperature above 61°F. The hottest day of the year is July 22, with an average high of 71°F and low of 54°F.

The cold season lasts for 3.8 months, from November 22 to March 14, with an average daily high temperature below 32°F. The coldest day of the year is February 3, with an average low of 11°F and high of 22°F.

Average High and Low Temperature

Average High and Low Temperature in JämsäwarmcoldcoldJanFebMarAprMayJunJulAugSepOctNovDec-20°F-20°F-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°FFeb 322°FFeb 322°FJul 2271°FJul 2271°F11°F11°F54°F54°FMay 2661°FMay 2661°FSep 161°FSep 161°FNov 2232°FNov 2232°FMar 1432°FMar 1432°F43°F43°F47°F47°F25°F25°F18°F18°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.

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

Average Hourly Temperature in JämsäJanFebMarAprMayJunJulAugSepOctNovDec12 AM12 AM4 AM4 AM8 AM8 AM12 PM12 PM4 PM4 PM8 PM8 PM12 AM12 AMNowNowfreezingfreezingvery coldcoldcoldcoolcomfortablevery cold
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.

Anchorage, Alaska, United States (3,933 miles away); Rimouski, Canada (3,475 miles); and Deer Lake, Canada (3,114 miles) are the far-away foreign places with temperatures most similar to Jämsä (view comparison).

Clouds

In Jämsä, 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 Jämsä begins around April 11 and lasts for 5.5 months, ending around September 25. On July 17, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 56% of the time, and overcast or mostly cloudy 44% of the time.

The cloudier part of the year begins around September 25 and lasts for 6.5 months, ending around April 11. On January 28, the cloudiest day of the year, the sky is overcast or mostly cloudy 84% of the time, and clear, mostly clear, or partly cloudy 16% of the time.

Cloud Cover Categories

Cloud Cover Categories in JämsäclearercloudiercloudierJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%Jul 1756%Jul 1756%Jan 2816%Jan 2816%Apr 1136%Apr 1136%Sep 2536%Sep 2536%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.

Precipitation

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

The wetter season lasts 6.5 months, from May 23 to December 5, with a greater than 26% chance of a given day being a wet day. The chance of a wet day peaks at 38% on July 29.

The drier season lasts 5.5 months, from December 5 to May 23. The smallest chance of a wet day is 15% on March 2.

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 Jämsä changes throughout the year.

Rain alone is the most common for 8.5 months, from March 19 to December 4. The highest chance of a day with rain alone is 38% on July 29.

Snow alone is the most common for 3.4 months, from December 4 to March 19. The highest chance of a day with snow alone is 16% on January 18.

Daily Chance of Precipitation

Daily Chance of Precipitation in JämsäsnowrainsnowJanFebMarAprMayJunJulAugSepOctNovDec0%0%10%10%20%20%30%30%40%40%50%50%60%60%70%70%80%80%90%90%100%100%Jul 2938%Jul 2938%Mar 215%Mar 215%Dec 426%Dec 426%May 2326%May 2326%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).

Rainfall

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. Jämsä experiences significant seasonal variation in monthly rainfall.

The rainy period of the year lasts for 9.0 months, from March 19 to December 20, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around July 20, with an average total accumulation of 3.0 inches.

The rainless period of the year lasts for 3.0 months, from December 20 to March 19. The least rain falls around February 1, with an average total accumulation of 0.2 inches.

Average Monthly Rainfall

Average Monthly Rainfall in JämsärainJanFebMarAprMayJunJulAugSepOctNovDec0 in0 in1 in1 in2 in2 in3 in3 in4 in4 in5 in5 in6 in6 inJul 203.0 inJul 203.0 inFeb 10.2 inFeb 10.2 inMar 190.5 inMar 190.5 inDec 200.5 inDec 200.5 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 liquid-equivalent snowfall.

Snowfall

We report snowfall in liquid-equivalent terms. The actual depth of new snowfall is typically between 5 and 10 times the liquid-equivalent amount, assuming the ground is frozen. Colder, drier snow tends to be on the higher end of that range and warmer, wetter snow on the lower end.

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

The snowy period of the year lasts for 6.5 months, from October 12 to April 27, with a sliding 31-day liquid-equivalent snowfall of at least 0.1 inches. The most snow falls during the 31 days centered around January 16, with an average total liquid-equivalent accumulation of 0.8 inches.

The snowless period of the year lasts for 5.5 months, from April 27 to October 12. The least snow falls around July 30, with an average total liquid-equivalent accumulation of 0.0 inches.

Average Liquid-Equivalent Monthly Snowfall

Average Liquid-Equivalent Monthly Snowfall in JämsäsnowsnowJanFebMarAprMayJunJulAugSepOctNovDec0.0 in0.0 in0.5 in0.5 in1.0 in1.0 in1.5 in1.5 in2.0 in2.0 in2.5 in2.5 in3.0 in3.0 inJan 160.8 inJan 160.8 inJul 300.0 inJul 300.0 inOct 120.1 inOct 120.1 inApr 270.1 inApr 270.1 in
The average liquid-equivalent 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.

Sun

The length of the day in Jämsä varies extremely over the course of the year. In 2021, the shortest day is December 21, with 5 hours, 12 minutes of daylight; the longest day is June 21, with 19 hours, 41 minutes of daylight.

Hours of Daylight and Twilight

Hours of Daylight and Twilight in JämsäJanFebMarAprMayJunJulAugSepOctNovDec0 hr24 hr4 hr20 hr8 hr16 hr12 hr12 hr16 hr8 hr20 hr4 hr24 hr0 hr12 hr, 8 minMar 2012 hr, 8 minMar 2019 hr, 41 minJun 2119 hr, 41 minJun 2112 hr, 16 minSep 2212 hr, 16 minSep 225 hr, 12 minDec 215 hr, 12 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.

The earliest sunrise is at 3:30 AM on June 19, and the latest sunrise is 6 hours, 12 minutes later at 9:42 AM on December 26. The earliest sunset is at 2:52 PM on December 17, and the latest sunset is 8 hours, 19 minutes later at 11:11 PM on June 22.

Daylight saving time (DST) is observed in Jämsä during 2021, starting in the spring on March 28, lasting 7.1 months, and ending in the fall on October 31.

Sunrise & Sunset with Twilight and Daylight Saving Time

Sunrise & Sunset with Twilight and Daylight Saving Time in JämsäJanFebMarAprMayJunJulAugSepOctNovDec2 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AMJun 193:30 AMJun 193:30 AM11:11 PMJun 2211:11 PMJun 22Dec 172:52 PMDec 172:52 PM9:42 AMDec 269:42 AMDec 26Mar 28DSTMar 28DSTDSTOct 31DSTOct 31daynightnightnightnightSolarMidnightSolarMidnightSolarNoonSunriseSunsetNowNow
The solar day over the course of the year 2021. 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.

Moon

The figure below presents a compact representation of key lunar data for 2021. 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

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.

Humidity

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.

The perceived humidity level in Jämsä, as measured by the percentage of time in which the humidity comfort level is muggy, oppressive, or miserable, does not vary significantly over the course of the year, staying within 1% of 1% throughout.

Humidity Comfort Levels

Humidity Comfort Levels in JämsäJanFebMarAprMayJunJulAugSepOctNovDec0%0%10%10%20%20%30%30%40%40%50%50%60%60%70%70%80%80%90%90%100%100%Mar 170%Mar 170%Jul 251%Jul 251%drydry
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.

Wind

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 Jämsä experiences mild seasonal variation over the course of the year.

The windier part of the year lasts for 6.7 months, from November 19 to June 9, with average wind speeds of more than 6.0 miles per hour. The windiest day of the year is April 6, with an average hourly wind speed of 6.7 miles per hour.

The calmer time of year lasts for 5.3 months, from June 9 to November 19. The calmest day of the year is July 30, with an average hourly wind speed of 5.3 miles per hour.

Average Wind Speed

Average Wind Speed in JämsäwindywindyJanFebMarAprMayJunJulAugSepOctNovDec0 mph0 mph1 mph1 mph2 mph2 mph3 mph3 mph4 mph4 mph5 mph5 mph6 mph6 mph7 mph7 mph8 mph8 mph9 mph9 mph10 mph10 mphApr 66.7 mphApr 66.7 mphJul 305.3 mphJul 305.3 mphNov 196.0 mphNov 196.0 mphJun 96.0 mphJun 96.0 mphNowNow
The average of mean hourly wind speeds (dark gray line), with 25th to 75th and 10th to 90th percentile bands.

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

The wind is most often from the west for 1.5 months, from May 12 to June 26, with a peak percentage of 32% on June 4. The wind is most often from the south for 11 months, from June 26 to May 12, with a peak percentage of 34% on January 1.

Wind Direction

Wind Direction in JämsäSWSJanFebMarAprMayJunJulAugSepOctNovDec0%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).

Best Time of Year to Visit

To characterize how pleasant the weather is in Jämsä 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 Jämsä for general outdoor tourist activities is from late June to mid August, with a peak score in the third week of July.

Tourism Score

Tourism Score in Jämsäbest timeJanFebMarAprMayJunJulAugSepOctNovDec002244668810106.46.40.00.0NowNowprecipitationprecipitationcloudscloudstemperaturetemperaturetourism 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 Jämsä for hot-weather activities is from mid to late July, with a peak score in the third week of July.

Beach/Pool Score

Beach/Pool Score in JämsäJanFebMarAprMayJunJulAugSepOctNovDec002244668810102.72.70.00.0NowNowprecipitationprecipitationcloudsclouds beach/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.

Growing Season

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 Jämsä typically lasts for 4.3 months (134 days), from around May 14 to around September 25, rarely starting before April 27 or after May 31, and rarely ending before September 5 or after October 16.

Time Spent in Various Temperature Bands and the Growing Season

Time Spent in Various Temperature Bands and the Growing Season in Jämsägrowing seasonJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%May 1450%May 1450%Sep 2550%Sep 2550%May 3190%May 3190%Sep 590%Sep 590%Apr 2710%Apr 2710%Oct 1610%Oct 1610%0%Feb 160%Feb 16Jul 20100%Jul 20100%NowNowfrigidfreezingvery coldcoolcoldcomfortablewarm
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 Jämsä should appear around May 22, only rarely appearing before May 12 or after June 4.

Growing Degree Days

Growing Degree Days in JämsäJanFebMarAprMayJunJulAugSepOctNovDec0°F0°F200°F200°F400°F400°F600°F600°F800°F800°F1,000°F1,000°F1,200°F1,200°F1,400°F1,400°FMay 2290°FMay 2290°FAug 9900°FAug 9900°FDec 311,196°FDec 311,196°FNowNow
The average growing degree days accumulated over the course of the year, with 25th to 75th and 10th to 90th percentile bands.

Solar Energy

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 3.1 months, from May 5 to August 10, with an average daily incident shortwave energy per square meter above 4.8 kWh. The brightest day of the year is June 20, with an average of 6.0 kWh.

The darker period of the year lasts for 4.6 months, from October 10 to February 28, with an average daily incident shortwave energy per square meter below 1.3 kWh. The darkest day of the year is December 21, with an average of 0.1 kWh.

Average Daily Incident Shortwave Solar Energy

Average Daily Incident Shortwave Solar Energy in JämsäbrightdarkdarkJanFebMarAprMayJunJulAugSepOctNovDec0 kWh0 kWh1 kWh1 kWh2 kWh2 kWh3 kWh3 kWh4 kWh4 kWh5 kWh5 kWh6 kWh6 kWh7 kWh7 kWh8 kWh8 kWh9 kWh9 kWhJun 206.0 kWhJun 206.0 kWhDec 210.1 kWhDec 210.1 kWhMay 54.8 kWhMay 54.8 kWhAug 104.8 kWhAug 104.8 kWhOct 101.3 kWhOct 101.3 kWhFeb 281.3 kWhFeb 281.3 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.

Topography

For the purposes of this report, the geographical coordinates of Jämsä are 61.864 deg latitude, 25.190 deg longitude, and 262 ft elevation.

The topography within 2 miles of Jämsä contains only modest variations in elevation, with a maximum elevation change of 289 feet and an average elevation above sea level of 322 feet. Within 10 miles contains only modest variations in elevation (515 feet). Within 50 miles also contains significant variations in elevation (640 feet).

The area within 2 miles of Jämsä is covered by cropland (35%), trees (34%), and artificial surfaces (28%), within 10 miles by trees (77%) and water (11%), and within 50 miles by trees (74%) and water (18%).

Data Sources

This report illustrates the typical weather in Jämsä, 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 4 weather stations near enough to contribute to our estimation of the temperature and dew point in Jämsä.

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

The stations contributing to this reconstruction are: Halli Airport (75%, 21 kilometers, west); Jyväskylä Airport (15%, 65 kilometers, northeast); Mikkeli Airport (7%, 108 kilometers, east); and Helsinki-Vantaa Airport (3.4%, 173 kilometers, south).

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 © Esri, with data from National Geographic, Esri, DeLorme, NAVTEQ, UNEP-WCMC, USGS, NASA, ESA, METI, NRCAN, GEBCO, NOAA, and iPC.

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.