Average Weather in Järvenpää Finland

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In Järvenpää, the summers are comfortable and partly cloudy and the winters are long, freezing, dry, and overcast. Over the course of the year, the temperature typically varies from 14°F to 73°F and is rarely below -8°F or above 83°F.

The warm season lasts for 3.3 months, from May 24 to September 2, with an average daily high temperature above 63°F. The hottest day of the year is July 21, with an average high of 73°F and low of 54°F.

The cold season lasts for 3.9 months, from November 20 to March 17, with an average daily high temperature below 35°F. The coldest day of the year is February 7, with an average low of 14°F and high of 26°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.

In Järvenpää, 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 Järvenpää begins around April 21 and lasts for 5.4 months, ending around October 1. On July 18, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 58% of the time, and overcast or mostly cloudy 42% of the time.

The cloudier part of the year begins around October 1 and lasts for 6.7 months, ending around April 21. On January 23, the cloudiest day of the year, the sky is overcast or mostly cloudy 79% of the time, and clear, mostly clear, or partly cloudy 21% of the time.

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

The wetter season lasts 7.6 months, from June 4 to January 24, with a greater than 25% chance of a given day being a wet day. The chance of a wet day peaks at 31% on November 9.

The drier season lasts 4.3 months, from January 24 to June 4. The smallest chance of a wet day is 18% on February 26.

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 Järvenpää changes throughout the year.

Rain alone is the most common for 10 months, from March 7 to January 6. The highest chance of a day with rain alone is 29% on August 14.

Snow alone is the most common for 2.0 months, from January 6 to March 7. The highest chance of a day with snow alone is 12% on January 22.

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. Järvenpää experiences some seasonal variation in monthly rainfall.

The rainy period of the year lasts for 11 months, from March 5 to January 27, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around August 11, with an average total accumulation of 2.1 inches.

The rainless period of the year lasts for 1.3 months, from January 27 to March 5. The least rain falls around February 15, with an average total accumulation of 0.4 inches.

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. Järvenpää experiences some seasonal variation in monthly liquid-equivalent snowfall.

The snowy period of the year lasts for 6.1 months, from October 18 to April 20, 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 23, with an average total liquid-equivalent accumulation of 0.7 inches.

The snowless period of the year lasts for 5.9 months, from April 20 to October 18. The least snow falls around July 19, with an average total liquid-equivalent accumulation of 0.0 inches.

The length of the day in Järvenpää varies extremely over the course of the year. In 2017, the shortest day is December 21, with 5 hours, 43 minutes of daylight; the longest day is June 21, with 19 hours, 3 minutes of daylight.

The earliest sunrise is at 3:49 AM on June 19, and the latest sunrise is 5 hours, 38 minutes later at 9:27 AM on December 27. The earliest sunset is at 3:07 PM on December 16, and the latest sunset is 7 hours, 45 minutes later at 10:53 PM on June 22.

Daylight saving time (DST) is observed in Järvenpää during 2017, starting in the spring on March 26, lasting 7.1 months, and ending in the fall on October 29.

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 Järvenpää, 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.

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

The windier part of the year lasts for 6.5 months, from September 22 to April 7, with average wind speeds of more than 3.2 miles per hour. The windiest day of the year is December 14, with an average hourly wind speed of 3.8 miles per hour.

The calmer time of year lasts for 5.5 months, from April 7 to September 22. The calmest day of the year is July 19, with an average hourly wind speed of 2.7 miles per hour.

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

The wind is most often from the south for 2.9 months, from January 25 to April 21; for 1.9 weeks, from July 17 to July 30; for 1.6 weeks, from August 31 to September 11; for 1.1 weeks, from September 22 to September 30; and for 2.5 months, from October 6 to December 22, with a peak percentage of 35% on November 25. The wind is most often from the west for 2.9 months, from April 21 to July 17; for 1.0 months, from July 30 to August 31; for 1.6 weeks, from September 11 to September 22; for 6.0 days, from September 30 to October 6; and for 1.1 months, from December 22 to January 25, with a peak percentage of 34% on June 4.

Järvenpää 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 2.6 months, from July 1 to September 18, with an average temperature above 56°F. The day of the year with the warmest water is August 6, with an average temperature of 63°F.

The time of year with cooler water lasts for 4.5 months, from December 15 to May 1, with an average temperature below 38°F. The day of the year with the coolest water is March 1, with an average temperature of 32°F.

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 3.2 months, from May 4 to August 10, with an average daily incident shortwave energy per square meter above 4.9 kWh. The brightest day of the year is July 2, with an average of 6.1 kWh.

The darker period of the year lasts for 4.5 months, from October 13 to February 27, with an average daily incident shortwave energy per square meter below 1.4 kWh. The darkest day of the year is December 21, with an average of 0.1 kWh.

For the purposes of this report, the geographical coordinates of Järvenpää are 60.474 deg latitude, 25.090 deg longitude, and 164 ft elevation.

The topography within 2 miles of Järvenpää contains only modest variations in elevation, with a maximum elevation change of 138 feet and an average elevation above sea level of 173 feet. Within 10 miles also contains only modest variations in elevation (374 feet). Within 50 miles contains only modest variations in elevation (755 feet).

The area within 2 miles of Järvenpää is covered by artificial surfaces (62%), trees (21%), and cropland (10%), within 10 miles by trees (47%) and cropland (36%), and within 50 miles by trees (46%) and water (30%).

This report illustrates the typical weather in Järvenpää, 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 3 weather stations near enough to contribute to our estimation of the temperature and dew point in Järvenpää.

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

The stations contributing to this reconstruction are: Helsinki-Vantaa Airport (89%, 19 kilometers, south); Utti Airport (6%, 111 kilometers, northeast); and Tampere–Pirkkala Airport (4.8%, 132 kilometers, northwest).

Other Data

All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Tables of the Sun, Moon and Planets , 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 aiports 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.