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Average Weather in Fort Irwin California, United States

In Fort Irwin, the summers are sweltering and mostly clear, the winters are cold and partly cloudy, and it is dry year round. Over the course of the year, the temperature typically varies from 32°F to 100°F and is rarely below 23°F or above 106°F.

Temperature

The hot season lasts for 3.4 months, from June 4 to September 17, with an average daily high temperature above 90°F. The hottest day of the year is July 19, with an average high of 100°F and low of 71°F.

The cold season lasts for 3.1 months, from November 20 to February 24, with an average daily high temperature below 63°F. The coldest day of the year is December 27, with an average low of 32°F and high of 54°F.

Average High and Low Temperature

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 Fort IrwinJanFebMarAprMayJunJulAugSepOctNovDec12 AM4 AM8 AM12 PM4 PM8 PM12 AMhotcoldcoolwarmvery coldswelteringcomfortable
The average hourly temperature, color coded into bands: 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 shaded overlays indicate night and civil twilight.

Clouds

In Fort Irwin, 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 Fort Irwin begins around April 26 and lasts for 6.3 months, ending around November 3. On September 7, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 90% of the time, and overcast or mostly cloudy 10% of the time.

The cloudier part of the year begins around November 3 and lasts for 5.7 months, ending around April 26. On February 21, the cloudiest day of the year, the sky is overcast or mostly cloudy 40% of the time, and clear, mostly clear, or partly cloudy 60% of the time.

Cloud Cover Categories

Cloud Cover Categories in Fort IrwinclearercloudiercloudierJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%Sep 790%Sep 790%Feb 2160%Feb 2160%Apr 2674%Apr 2674%Nov 375%Nov 375%clearovercastmostly clear
The percentage of time spent in each cloud cover band, categorized by the percentage of the sky covered by clouds: clear < 20% < mostly clear < 40% < partly cloudy < 60% < mostly cloudy < 80% < overcast.

Precipitation

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

The wetter season lasts 7.5 months, from August 4 to March 22, with a greater than 6% chance of a given day being a wet day. The chance of a wet day peaks at 12% on February 21.

The drier season lasts 4.5 months, from March 22 to August 4. The smallest chance of a wet day is 1% on June 13.

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 throughout the year is rain alone, with a peak probability of 12% on February 21.

Daily Chance of Precipitation

Daily Chance of Precipitation in Fort IrwinwetwetdryJanFebMarAprMayJunJulAugSepOctNovDec0%10%20%30%40%50%60%70%80%90%100%Feb 2112%Feb 2112%Jun 131%Jun 131%Jan 19%Jan 19%Aug 46%Aug 46%rain
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. Fort Irwin experiences some seasonal variation in monthly rainfall.

The rainy period of the year lasts for 3.3 months, from December 6 to March 17, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around February 19, with an average total accumulation of 0.9 inches.

The rainless period of the year lasts for 8.7 months, from March 17 to December 6. The least rain falls around June 12, with an average total accumulation of 0.1 inches.

Average Monthly Rainfall

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.

Sun

The length of the day in Fort Irwin varies significantly over the course of the year. In 2017, the shortest day is December 21, with 9 hours, 47 minutes of daylight; the longest day is June 20, with 14 hours, 32 minutes of daylight.

Hours of Daylight and Twilight

Hours of Daylight and Twilight in Fort IrwinJanFebMarAprMayJunJulAugSepOctNovDec0 hr24 hr4 hr20 hr8 hr16 hr12 hr12 hr16 hr8 hr20 hr4 hr24 hr0 hr12 hr, 7 minMar 2012 hr, 7 minMar 2014 hr, 32 minJun 2014 hr, 32 minJun 2012 hr, 8 minSep 2212 hr, 8 minSep 229 hr, 47 minDec 219 hr, 47 minDec 21nightnightday
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 5:31 AM on June 12, and the latest sunrise is 1 hour, 40 minutes later at 7:11 AM on November 4. The earliest sunset is at 4:34 PM on December 5, and the latest sunset is 3 hours, 31 minutes later at 8:05 PM on June 28.

Daylight saving time (DST) is observed in Fort Irwin during 2017, starting in the spring on March 12, lasting 7.8 months, and ending in the fall on November 5.

Sunrise & Sunset with Twilight and Daylight Saving Time

Sunrise & Sunset with Twilight and Daylight Saving Time in Fort IrwinJanFebMarAprMayJunJulAugSepOctNovDec12 AM2 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AMJun 125:31 AMJun 125:31 AM8:05 PMJun 288:05 PMJun 28Dec 54:34 PMDec 54:34 PM7:11 AMNov 47:11 AMNov 4Mar 12DSTMar 12DSTDSTNov 5DSTNov 5daynightnightnightnightSolarMidnightSolarMidnightSolarNoonSunriseSunset
The solar day over the course of the year 2017. 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.

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 Fort Irwin, 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 Fort IrwinJanFebMarAprMayJunJulAugSepOctNovDec0%10%20%30%40%50%60%70%80%90%100%Mar 250%Mar 250%Aug 242%Aug 242%drydry
The percentage of time spent at various humidity comfort levels, categorized by dew point: dry < 55°F < comfortable < 60°F < humid < 65°F < muggy < 70°F < oppressive < 75°F < miserable.

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 Fort Irwin experiences significant seasonal variation over the course of the year.

The windier part of the year lasts for 4.6 months, from March 14 to August 1, with average wind speeds of more than 8.6 miles per hour. The windiest day of the year is June 10, with an average hourly wind speed of 10.3 miles per hour.

The calmer time of year lasts for 7.4 months, from August 1 to March 14. The calmest day of the year is January 10, with an average hourly wind speed of 6.9 miles per hour.

Average Wind Speed

Average Wind Speed in Fort IrwinwindyJanFebMarAprMayJunJulAugSepOctNovDec0 mph2 mph4 mph6 mph8 mph10 mph12 mph14 mph16 mph18 mphJun 1010.3 mphJun 1010.3 mphJan 106.9 mphJan 106.9 mphMar 148.6 mphMar 148.6 mphAug 18.6 mphAug 18.6 mph
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 Fort Irwin varies throughout the year.

The wind is most often from the west for 8.5 months, from February 15 to October 29, with a peak percentage of 70% on June 16. The wind is most often from the north for 3.5 months, from October 29 to February 15, with a peak percentage of 53% on January 1.

Wind Direction

Wind Direction in Fort IrwinNWNJanFebMarAprMayJunJulAugSepOctNovDec0%100%20%80%40%60%60%40%80%20%100%0%westsouthnortheast
The percentage of hours in which the mean wind direction is from each of the four cardinal wind directions (north, east, south, and west), excluding hours in which the mean wind speed is less than 1 mph. The lightly tinted areas at the boundaries are the percentage of hours spent in the implied intermediate directions (northeast, southeast, southwest, and northwest).

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 3.6 months, from April 25 to August 13, with an average daily incident shortwave energy per square meter above 7.6 kWh. The brightest day of the year is June 17, with an average of 8.8 kWh.

The darker period of the year lasts for 3.2 months, from November 4 to February 11, with an average daily incident shortwave energy per square meter below 4.1 kWh. The darkest day of the year is December 22, with an average of 3.0 kWh.

Average Daily Incident Shortwave Solar Energy

Average Daily Incident Shortwave Solar Energy in Fort IrwinbrightdarkdarkJanFebMarAprMayJunJulAugSepOctNovDec0 kWh1 kWh2 kWh3 kWh4 kWh5 kWh6 kWh7 kWh8 kWh9 kWh10 kWhJun 178.8 kWhJun 178.8 kWhDec 223.0 kWhDec 223.0 kWhApr 257.6 kWhApr 257.6 kWhAug 137.6 kWhAug 137.6 kWhNov 44.1 kWhNov 44.1 kWhFeb 114.1 kWhFeb 114.1 kWh
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 Fort Irwin are 35.263 deg latitude, -116.685 deg longitude, and 2,592 ft elevation.

The topography within 2 miles of Fort Irwin contains very significant variations in elevation, with a maximum elevation change of 951 feet and an average elevation above sea level of 2,569 feet. Within 10 miles contains very significant variations in elevation (3,415 feet). Within 50 miles also contains extreme variations in elevation (6,493 feet).

The area within 2 miles of Fort Irwin is covered by shrubs (88%) and bare soil (12%), within 10 miles by shrubs (85%) and bare soil (15%), and within 50 miles by shrubs (92%).

Data Sources

This report illustrates the typical weather in Fort Irwin, 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 Fort Irwin.

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

The stations contributing to this reconstruction are: Bicycle Lake Army Airfield (31%, 5.2 kilometers, northeast); Barstow Daggett County Airport (52%, 46 kilometers, south); and Ridgecrest Community Hospital Heliport (18%, 103 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.

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.