Average Weather in April in Shelby Montana, United States
Daily high temperatures increase by 10°F, from 50°F to 61°F, rarely falling below 35°F or exceeding 75°F.
Daily low temperatures increase by 8°F, from 28°F to 36°F, rarely falling below 16°F or exceeding 45°F.
For reference, on July 31, the hottest day of the year, temperatures in Shelby typically range from 54°F to 83°F, while on January 1, the coldest day of the year, they range from 13°F to 31°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
The month of April in Shelby experiences gradually decreasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy decreasing from 60% to 55%.
The clearest day of the month is April 30, with clear, mostly clear, or partly cloudy conditions 45% of the time.
For reference, on March 17, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 62%, while on July 23, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 75%.
Cloud Cover Categories in April
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Shelby, the chance of a wet day over the course of April is gradually increasing, starting the month at 11% and ending it at 14%.
For reference, the year's highest daily chance of a wet day is 29% on June 5, and its lowest chance is 3% on January 31.
Over the course of April in Shelby, the chance of a day with only rain increases from 6% to 11%, the chance of a day with mixed snow and rain remains an essentially constant 2% throughout, and the chance of a day with only snow decreases from 3% to 1%.
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 Shelby is increasing, starting the month at 0.4 inches, when it rarely exceeds 0.9 inches, and ending the month at 0.9 inches, when it rarely exceeds 2.0 inches or falls below 0.2 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 Shelby is essentially constant, remaining about 0.1 inches throughout, and rarely exceeding 0.4 inches or falling below -0.0 inches.
Average Monthly Liquid-Equivalent Snowfall in April
Over the course of April in Shelby, 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, 38 minutes, implying an average daily increase of 3 minutes, 23 seconds, and weekly increase of 23 minutes, 41 seconds.
The shortest day of the month is April 1, with 12 hours, 53 minutes of daylight and the longest day is April 30, with 14 hours, 31 minutes of daylight.
Hours of Daylight and Twilight in April
The latest sunrise of the month in Shelby is 7:05 AM on April 1 and the earliest sunrise is 56 minutes earlier at 6:09 AM on April 30.
The earliest sunset is 7:58 PM on April 1 and the latest sunset is 42 minutes later at 8:40 PM on April 30.
Daylight saving time is observed in Shelby during 2018, 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 5:25 AM and sets 16 hours, 8 minutes later, at 9:33 PM, while on December 21, the shortest day of the year, it rises at 8:16 AM and sets 8 hours, 18 minutes later, at 4:34 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 Shelby is essentially constant during April, remaining around 0% throughout.
For reference, on June 30, the muggiest day of the year, there are muggy conditions 0% of the time, while on January 1, the least muggy day of the year, there are muggy conditions 0% of the time.
Humidity Comfort Levels in April
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 Shelby is essentially constant during April, remaining within 0.2 miles per hour of 11.3 miles per hour throughout.
For reference, on January 18, the windiest day of the year, the daily average wind speed is 12.1 miles per hour, while on August 4, the calmest day of the year, the daily average wind speed is 8.5 miles per hour.
Average Wind Speed in April
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 Shelby typically lasts for 4.4 months (135 days), from around May 12 to around September 24, rarely starting before April 26 or after May 28, and rarely ending before September 6 or after October 13.
The month of April in Shelby is more likely than not fully outside of the growing season, with the chance that a given day is in the growing season increasing from 0% to 17% over the course of the month.
Time Spent in Various Temperature Bands and the Growing Season in April
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 Shelby are gradually increasing during April, increasing by 68°F, from 24°F to 93°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 Shelby is increasing during April, rising by 1.4 kWh, from 4.5 kWh to 5.9 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 Shelby are 48.505 deg latitude, -111.857 deg longitude, and 3,419 ft elevation.
The topography within 2 miles of Shelby contains only modest variations in elevation, with a maximum elevation change of 272 feet and an average elevation above sea level of 3,373 feet. Within 10 miles contains only modest variations in elevation (787 feet). Within 50 miles contains significant variations in elevation (4,245 feet).
The area within 2 miles of Shelby is covered by grassland (83%) and cropland (12%), within 10 miles by grassland (68%) and cropland (30%), and within 50 miles by grassland (52%) and cropland (46%).
This report illustrates the typical weather in Shelby 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 Shelby.
For each station, the records are corrected for the elevation difference between that station and Shelby 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 Shelby is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Shelby and a given station.
The stations contributing to this reconstruction are: Cut Bank Municipal Airport (45%, 40 kilometers, west); Milk River (20%, 71 kilometers, north); Masinasin AGDM (20%, 72 kilometers, north); and Julie (15%, 87 kilometers, south).
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.