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Average Weather at Mount Shasta California, United States

At Mount Shasta, the summers are warm, dry, and mostly clear and the winters are long, chilly, wet, and partly cloudy. Over the course of the year, the temperature typically varies from 27°F to 85°F and is rarely below 18°F or above 93°F.

The warm season lasts for 3.0 months, from June 18 to September 18, with an average daily high temperature above 76°F. The hottest day of the year is August 4, with an average high of 85°F and low of 51°F.

The cold season lasts for 3.8 months, from November 13 to March 6, with an average daily high temperature below 50°F. The coldest day of the year is December 31, with an average low of 27°F and high of 42°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 at Mount ShastaJanFebMarAprMayJunJulAugSepOctNovDec12 AM4 AM8 AM12 PM4 PM8 PM12 AMwarmcoldcoolchillyfreezingcomfortable
The average hourly temperature, color coded into bands: frigid < 15°F < freezing < 32°F < chilly < 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

At Mount Shasta, the average percentage of the sky covered by clouds experiences extreme seasonal variation over the course of the year.

The clearer part of the year at Mount Shasta begins around June 1 and lasts for 4.5 months, ending around October 16. On August 3, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 89% of the time, and overcast or mostly cloudy 11% of the time.

The cloudier part of the year begins around October 16 and lasts for 7.5 months, ending around June 1. On January 9, the cloudiest day of the year, the sky is overcast or mostly cloudy 65% of the time, and clear, mostly clear, or partly cloudy 34% of the time.

Cloud Cover Categories

Cloud Cover Categories at Mount ShastaclearercloudiercloudierJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%Aug 389%Aug 389%Jan 934%Jan 934%Jun 161%Jun 161%Oct 1661%Oct 1661%partly cloudyclearovercastmostly cloudymostly 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 at Mount Shasta varies significantly throughout the year.

The wetter season lasts 6.4 months, from October 25 to May 7, with a greater than 20% chance of a given day being a wet day. The chance of a wet day peaks at 36% on February 28.

The drier season lasts 5.6 months, from May 7 to October 25. The smallest chance of a wet day is 3% on August 8.

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 24% on November 8.

Daily Chance of Precipitation

Daily Chance of Precipitation at Mount ShastawetwetdryJanFebMarAprMayJunJulAugSepOctNovDec0%10%20%30%40%50%60%70%80%90%100%Feb 2836%Feb 2836%Aug 83%Aug 83%Jan 131%Jan 131%Oct 2520%Oct 2520%May 720%May 720%rainmixedsnow
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. Mount Shasta experiences extreme seasonal variation in monthly rainfall.

The rainy period of the year lasts for 9.4 months, from September 13 to June 24, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around December 9, with an average total accumulation of 4.4 inches.

The rainless period of the year lasts for 2.6 months, from June 24 to September 13. The least rain falls around July 31, 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.

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. Mount Shasta experiences significant seasonal variation in monthly liquid-equivalent snowfall.

The snowy period of the year lasts for 5.8 months, from October 29 to April 22, with a sliding 31-day liquid-equivalent snowfall of at least 0.1 inches. The most snow falls during the 31 days centered around December 31, with an average total liquid-equivalent accumulation of 1.0 inches.

The snowless period of the year lasts for 6.2 months, from April 22 to October 29. The least snow falls around August 2, with an average total liquid-equivalent accumulation of 0.0 inches.

Average Liquid-Equivalent Monthly Snowfall

Average Liquid-Equivalent Monthly Snowfall at Mount ShastasnowsnowJanFebMarAprMayJunJulAugSepOctNovDec0 in1 in2 in3 in4 in5 inDec 311.0 inDec 311.0 inAug 20.0 inAug 20.0 inOct 290.1 inOct 290.1 inApr 220.1 inApr 220.1 in
The average liquid-equivalent snowfall (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 rainfall.

Sun

The length of the day at Mount Shasta varies significantly over the course of the year. In 2017, the shortest day is December 21, with 9 hours, 11 minutes of daylight; the longest day is June 20, with 15 hours, 10 minutes of daylight.

Hours of Daylight and Twilight

Hours of Daylight and Twilight at Mount ShastaJanFebMarAprMayJunJulAugSepOctNovDec0 hr24 hr4 hr20 hr8 hr16 hr12 hr12 hr16 hr8 hr20 hr4 hr24 hr0 hr12 hr, 7 minMar 2012 hr, 7 minMar 2015 hr, 10 minJun 2015 hr, 10 minJun 2012 hr, 9 minSep 2212 hr, 9 minSep 229 hr, 11 minDec 219 hr, 11 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 5:35 AM on June 14, and the latest sunrise is 2 hours, 9 minutes later at 7:44 AM on November 4. The earliest sunset is at 4:39 PM on December 7, and the latest sunset is 4 hours, 7 minutes later at 8:46 PM on June 27.

Daylight saving time (DST) is observed at Mount Shasta 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 at Mount ShastaJanFebMarAprMayJunJulAugSepOctNovDec12 AM2 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AMJun 145:35 AMJun 145:35 AM8:46 PMJun 278:46 PMJun 27Dec 74:39 PMDec 74:39 PM7:44 AMNov 47:44 AMNov 4Mar 12DSTMar 12DSTDSTNov 5DSTNov 5daynightnightnightnight
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 at Mount Shasta, 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, remaining a virtually constant 0% throughout.

Humidity Comfort Levels

Humidity Comfort Levels at Mount ShastaJanFebMarAprMayJunJulAugSepOctNovDec0%10%20%30%40%50%60%70%80%90%100%Jan 10%Jan 10%Jul 110%Jul 110%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 at Mount Shasta does not vary significantly over the course of the year, remaining within 0.3 miles per hour of 2.4 miles per hour throughout.

Average Wind Speed

Average Wind Speed at Mount ShastaJanFebMarAprMayJunJulAugSepOctNovDec0.0 mph0.5 mph1.0 mph1.5 mph2.0 mph2.5 mph3.0 mph3.5 mph4.0 mph4.5 mphMar 162.7 mphMar 162.7 mphAug 62.0 mphAug 62.0 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 at Mount Shasta varies throughout the year.

The wind is most often from the north for 6.2 months, from April 17 to October 24, with a peak percentage of 48% on June 9. The wind is most often from the south for 5.8 months, from October 24 to April 17, with a peak percentage of 41% on January 1.

Wind Direction

Wind Direction at Mount ShastaSNSJanFebMarAprMayJunJulAugSepOctNovDec0%100%20%80%40%60%60%40%80%20%100%0%eastwestnorthsouth
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 3.4 months, from May 14 to August 25, with an average daily incident shortwave energy per square meter above 7.1 kWh. The brightest day of the year is June 30, with an average of 8.4 kWh.

The darker period of the year lasts for 3.7 months, from October 31 to February 19, with an average daily incident shortwave energy per square meter below 3.1 kWh. The darkest day of the year is December 20, with an average of 1.7 kWh.

Average Daily Incident Shortwave Solar Energy

Average Daily Incident Shortwave Solar Energy at Mount ShastabrightdarkdarkJanFebMarAprMayJunJulAugSepOctNovDec0 kWh1 kWh2 kWh3 kWh4 kWh5 kWh6 kWh7 kWh8 kWh9 kWh10 kWhJun 308.4 kWhJun 308.4 kWhDec 201.7 kWhDec 201.7 kWhMay 147.1 kWhMay 147.1 kWhAug 257.1 kWhAug 257.1 kWhOct 313.1 kWhOct 313.1 kWhFeb 193.1 kWhFeb 193.1 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 Mount Shasta are 41.316 deg latitude, -122.316 deg longitude, and 3,812 ft elevation.

The topography within 2 miles of Mount Shasta contains very significant variations in elevation, with a maximum elevation change of 1,152 feet and an average elevation above sea level of 3,702 feet. Within 10 miles contains very significant variations in elevation (11,985 feet). Within 50 miles also contains extreme variations in elevation (13,635 feet).

The area within 2 miles of Mount Shasta is covered by shrubs (76%) and trees (15%), within 10 miles by trees (52%) and shrubs (41%), and within 50 miles by trees (49%) and shrubs (42%).

Data Sources

This report illustrates the typical weather at Mount Shasta, 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

Mount Shasta has a weather station that reported reliably enough during the analysis period that we have included it in our network. When available, historical temperature and dew point measurements are taken directly from this weather station. These records are obtained from NOAA's Integrated Surface Hourly data set, falling back on ICAO METAR records as required.

In the case of missing or erroneous measurements from this station, we fall back on records from nearby stations, adjusted according to typical seasonal and diurnal intra-station differences. For a given day of the year and hour of the day, the fallback station is selected to minimize the prediction error over the years for which there are measurements for both stations.

The stations on which we may fall back include but are not limited to Siskiyou County Airport, Redding Municipal Airport, Klamath Falls Airport, Rogue Valley International - Medford Airport, Red Bluff Municipal Airport, Sexton Summit,, Alturas Municipal Airport, and Jack Mc Namara Field.

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.