Average Weather in August in West Yellowstone Montana, United States
In West Yellowstone, the month of August is characterized by falling daily high temperatures, with daily highs decreasing by 5°F, from 77°F to 71°F over the course of the month, and rarely exceeding 84°F or dropping below 61°F.
Daily low temperatures decrease by 5°F, from 46°F to 41°F, rarely falling below 33°F or exceeding 52°F.
For reference, on July 30, the hottest day of the year, temperatures in West Yellowstone typically range from 46°F to 77°F, while on January 27, the coldest day of the year, they range from 7°F to 25°F.
Average High and Low Temperature in August
The figure below shows you a compact characterization of the hourly average temperatures for the quarter of the year centered on August. 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 August
The month of August in West Yellowstone experiences gradually increasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy increasing from 22% to 28%.
The clearest day of the month is August 1, with clear, mostly clear, or partly cloudy conditions 78% of the time.
For reference, on March 18, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 61%, while on July 26, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 79%.
Cloud Cover Categories in August
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In West Yellowstone, the chance of a wet day over the course of August is essentially constant, remaining around 19% throughout.
For reference, the year's highest daily chance of a wet day is 38% on June 1, and its lowest chance is 18% on September 10.
Probability of Precipitation in August
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 August in West Yellowstone is essentially constant, remaining about 0.9 inches throughout, and rarely exceeding 1.9 inches or falling below 0.2 inches.
The lowest average 31-day accumulation is 0.9 inches on August 12.
Average Monthly Rainfall in August
Over the course of August in West Yellowstone, the length of the day is rapidly decreasing. From the start to the end of the month, the length of the day decreases by 1 hour, 22 minutes, implying an average daily decrease of 2 minutes, 45 seconds, and weekly decrease of 19 minutes, 12 seconds.
The shortest day of the month is August 31, with 13 hours, 16 minutes of daylight and the longest day is August 1, with 14 hours, 38 minutes of daylight.
Hours of Daylight and Twilight in August
The earliest sunrise of the month in West Yellowstone is 6:11 AM on August 1 and the latest sunrise is 35 minutes later at 6:46 AM on August 31.
The latest sunset is 8:49 PM on August 1 and the earliest sunset is 47 minutes earlier at 8:02 PM on August 31.
Daylight saving time is observed in West Yellowstone during 2017, but it neither starts nor ends during August, so the entire month is in daylight saving time.
For reference, on June 21, the longest day of the year, the Sun rises at 5:39 AM and sets 15 hours, 34 minutes later, at 9:13 PM, while on December 21, the shortest day of the year, it rises at 7:58 AM and sets 8 hours, 48 minutes later, at 4:46 PM.
Sunrise & Sunset with Twilight in August
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 West Yellowstone is essentially constant during August, remaining around 0% throughout.
Humidity Comfort Levels in August
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 West Yellowstone is essentially constant during August, remaining within 0.2 miles per hour of 4.5 miles per hour throughout.
For reference, on December 1, the windiest day of the year, the daily average wind speed is 5.6 miles per hour, while on August 3, the calmest day of the year, the daily average wind speed is 4.3 miles per hour.
The lowest daily average wind speed during August is 4.3 miles per hour on August 4.
Average Wind Speed in August
Wind Direction in August
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 West Yellowstone typically lasts for 2.5 months (76 days), from around June 22 to around September 6, rarely starting before June 1 or after July 11, and rarely ending before August 18 or after September 25.
The month of August in West Yellowstone is more likely than not fully within the growing season, with the chance that a given day is in the growing season reaching a high of 100% on August 1.
Time Spent in Various Temperature Bands and the Growing Season in August
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 West Yellowstone is increasing during August, increasing by 310°F, from 595°F to 905°F, over the course of the month.
Growing Degree Days in August
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 West Yellowstone is decreasing during August, falling by 1.2 kWh, from 7.4 kWh to 6.2 kWh, over the course of the month.
Average Daily Incident Shortwave Solar Energy in August
For the purposes of this report, the geographical coordinates of West Yellowstone are 44.662 deg latitude, -111.104 deg longitude, and 6,667 ft elevation.
The topography within 2 miles of West Yellowstone contains only modest variations in elevation, with a maximum elevation change of 220 feet and an average elevation above sea level of 6,664 feet. Within 10 miles contains only modest variations in elevation (2,096 feet). Within 50 miles contains large variations in elevation (6,365 feet).
The area within 2 miles of West Yellowstone is covered by trees (58%) and shrubs (42%), within 10 miles by trees (54%) and shrubs (41%), and within 50 miles by trees (44%) and shrubs (41%).
This report illustrates the typical weather in West Yellowstone 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 6 weather stations near enough to contribute to our estimation of the temperature and dew point in West Yellowstone.
For each station, the records are corrected for the elevation difference between that station and West Yellowstone 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 West Yellowstone is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between West Yellowstone and a given station.
The stations contributing to this reconstruction are: West Yellowstone (35%, 56 kilometers, east); Driggs, Driggs-Reed Memorial Airport (18%, 102 kilometers, south); Rexburg Airport (14%, 108 kilometers, southwest); Gallatin Field Airport (11%, 125 kilometers, north); Mission Field (11%, 127 kilometers, northeast); and Dillon Airport (11%, 132 kilometers, northwest).
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.