Average Weather in April in Janesville Wisconsin, United States
Daily high temperatures increase by 13°F, from 52°F to 65°F, rarely falling below 38°F or exceeding 79°F.
Daily low temperatures increase by 10°F, from 34°F to 43°F, rarely falling below 23°F or exceeding 56°F.
For reference, on July 20, the hottest day of the year, temperatures in Janesville typically range from 63°F to 83°F, while on January 22, the coldest day of the year, they range from 14°F to 28°F.
Average High and Low Temperature in April
The figure below shows you a compact characterization of the hourly average temperatures for the quarter of the year centered on April. The horizontal axis is the day, 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 April
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 month of April in Janesville experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 53% throughout the month.
The clearest day of the month is April 10, with clear, mostly clear, or partly cloudy conditions 48% of the time.
For reference, on December 31, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 59%, while on August 26, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 68%.
Cloud Cover Categories in April
0% clear 20% mostly clear 40% partly cloudy 60% mostly cloudy 80% overcast 100%
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Janesville, the chance of a wet day over the course of April is rapidly increasing, starting the month at 25% and ending it at 32%.
For reference, the year's highest daily chance of a wet day is 38% on June 14, and its lowest chance is 12% on February 8.
Over the course of April in Janesville, the chance of a day with only rain increases from 22% to 32%, the chance of a day with mixed snow and rain decreases from 3% to 0%, and the chance of a day with only snow remains an essentially constant 1% throughout.
Probability of Precipitation in April
To show variation within the month and not just the monthly total, we show the rainfall accumulated over a sliding 31-day period centered around each day.
The average sliding 31-day rainfall during April in Janesville is increasing, starting the month at 2.4 inches, when it rarely exceeds 4.3 inches or falls below 0.8 inches, and ending the month at 3.1 inches, when it rarely exceeds 5.0 inches or falls below 1.3 inches.
Average Monthly Rainfall in April
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. As with rainfall, we consider the liquid-equivalent snowfall accumulated over a sliding 31-day period centered around each day.
The average sliding 31-day liquid-equivalent snowfall during April in Janesville is essentially constant, remaining about 0.1 inches throughout, and rarely exceeding 0.3 inches or falling below -0.0 inches.
Average Monthly Liquid-Equivalent Snowfall in April
Over the course of April in Janesville, the length of the day is rapidly increasing. From the start to the end of the month, the length of the day increases by 1 hour, 19 minutes, implying an average daily increase of 2 minutes, 44 seconds, and weekly increase of 19 minutes, 11 seconds.
The shortest day of the month is April 1, with 12 hours, 43 minutes of daylight and the longest day is April 30, with 14 hours, 3 minutes of daylight.
Hours of Daylight and Twilight in April
The latest sunrise of the month in Janesville is 6:38 AM on April 1 and the earliest sunrise is 46 minutes earlier at 5:52 AM on April 30.
The earliest sunset is 7:21 PM on April 1 and the latest sunset is 33 minutes later at 7:55 PM on April 30.
Daylight saving time is observed in Janesville during 2019, but it neither starts nor ends during April, so the entire month is in daylight saving time.
For reference, on June 21, the longest day of the year, the Sun rises at 5:18 AM and sets 15 hours, 19 minutes later, at 8:37 PM, while on December 22, the shortest day of the year, it rises at 7:23 AM and sets 9 hours, 2 minutes later, at 4:25 PM.
Sunrise & Sunset with Twilight and Daylight Saving Time in April
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 chance that a given day will be muggy in Janesville is essentially constant during April, remaining around 0% throughout.
For reference, on July 22, the muggiest day of the year, there are muggy conditions 43% of the time, while on November 16, the least muggy day of the year, there are muggy conditions 0% of the time.
Humidity Comfort Levels in April
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
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 Janesville is gradually decreasing during April, decreasing from 12.4 miles per hour to 11.6 miles per hour over the course of the month.
For reference, on March 24, the windiest day of the year, the daily average wind speed is 12.5 miles per hour, while on August 3, the calmest day of the year, the daily average wind speed is 7.8 miles per hour.
Average Wind Speed in April
The wind direction in Janesville during April is predominantly out of the north from April 1 to April 11 and the east from April 11 to April 30.
Wind Direction in April
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 Janesville typically lasts for 5.4 months (164 days), from around April 28 to around October 9, rarely starting before April 11 or after May 18, and rarely ending before September 22 or after October 26.
During April in Janesville, the chance that a given day is within the growing season is very rapidly increasing rising from 1% to 54% over the course of the month.
Time Spent in Various Temperature Bands and the Growing Season in April
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
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.
The average accumulated growing degree days in Janesville are gradually increasing during April, increasing by 115°F, from 36°F to 152°F, over the course of the month.
Growing Degree Days in April
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 in Janesville is increasing during April, rising by 1.1 kWh, from 4.7 kWh to 5.7 kWh, over the course of the month.
Average Daily Incident Shortwave Solar Energy in April
For the purposes of this report, the geographical coordinates of Janesville are 42.683 deg latitude, -89.019 deg longitude, and 846 ft elevation.
The topography within 2 miles of Janesville contains only modest variations in elevation, with a maximum elevation change of 161 feet and an average elevation above sea level of 825 feet. Within 10 miles also contains only modest variations in elevation (299 feet). Within 50 miles contains only modest variations in elevation (1,047 feet).
The area within 2 miles of Janesville is covered by artificial surfaces (92%), within 10 miles by cropland (84%), and within 50 miles by cropland (81%).
This report illustrates the typical weather in Janesville year round, 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 Janesville.
For each station, the records are corrected for the elevation difference between that station and Janesville 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 Janesville is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Janesville and a given station.
The stations contributing to this reconstruction are: Southern Wisconsin Regional Airport (88%, 7 kilometers, south); Dane County Regional Airport (4.1%, 58 kilometers, northwest); Burlington Municipal Airport (4.0%, 58 kilometers, east); and Watertown Municipal Airport (4.0%, 59 kilometers, northeast).
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.
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.