Climate and Average Weather Year Round in Shasta United States

In Shasta, the summers are hot, dry, and mostly clear and the winters are cold, wet, and partly cloudy. Over the course of the year, the temperature typically varies from 34°F to 97°F and is rarely below 26°F or above 106°F.

Based on the tourism score, the best time of year to visit Shasta for warm-weather activities is from mid June to early September.

The hot season lasts for 3.2 months, from June 12 to September 19, with an average daily high temperature above 88°F. The hottest month of the year in Shasta is July, with an average high of 96°F and low of 63°F.

The cool season lasts for 3.5 months, from November 14 to February 27, with an average daily high temperature below 61°F. The coldest month of the year in Shasta is December, with an average low of 35°F and high of 53°F.

In 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 in Shasta begins around May 28 and lasts for 4.7 months, ending around October 19.

The clearest month of the year in Shasta is August, during which on average the sky is clear, mostly clear, or partly cloudy 88% of the time.

The cloudier part of the year begins around October 19 and lasts for 7.3 months, ending around May 28.

The cloudiest month of the year in Shasta is January, during which on average the sky is overcast or mostly cloudy 59% of the time.

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

The wetter season lasts 6.0 months, from October 27 to April 29, with a greater than 21% chance of a given day being a wet day. The month with the most wet days in Shasta is February, with an average of 10.8 days with at least 0.04 inches of precipitation.

The drier season lasts 6.0 months, from April 29 to October 27. The month with the fewest wet days in Shasta is August, with an average of 0.8 days with at least 0.04 inches of precipitation.

Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. The month with the most days of rain alone in Shasta is February, with an average of 10.5 days. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 39% on February 28.

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. Shasta experiences extreme seasonal variation in monthly rainfall.

The rainy period of the year lasts for 9.6 months, from September 7 to June 25, with a sliding 31-day rainfall of at least 0.5 inches. The month with the most rain in Shasta is December, with an average rainfall of 6.8 inches.

The rainless period of the year lasts for 2.4 months, from June 25 to September 7. The month with the least rain in Shasta is August, with an average rainfall of 0.2 inches.

Snowfall

As with rainfall, we consider the snowfall accumulated over a sliding 31-day period centered around each day of the year. Shasta experiences some seasonal variation in monthly snowfall.

The snowy period of the year lasts for 1.0 months, from December 15 to January 15, with a sliding 31-day snowfall of at least 1.0 inches. The month with the most snow in Shasta is December, with an average snowfall of 1.1 inches.

The snowless period of the year lasts for 11 months, from January 15 to December 15. The least snow falls around July 26, with an average total accumulation of 0.0 inches.

The length of the day in Shasta varies significantly over the course of the year. In 2024, the shortest day is December 21, with 9 hours, 16 minutes of daylight; the longest day is June 20, with 15 hours, 5 minutes of daylight.

The earliest sunrise is at 5:38 AM on June 13, and the latest sunrise is 2 hours, 4 minutes later at 7:42 AM on November 2. The earliest sunset is at 4:42 PM on December 7, and the latest sunset is 4 hours, 2 minutes later at 8:44 PM on June 26.

Daylight saving time (DST) is observed in Shasta during 2024, starting in the spring on March 10, lasting 7.8 months, and ending in the fall on November 3.

The figure below presents a compact representation of key lunar data for 2024. The horizontal axis is the day, the vertical axis is the hour of the day, and the colored areas indicate when the moon is above the horizon. The vertical gray bars (new Moons) and blue bars (full Moons) indicate key Moon phases.

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 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.

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 Shasta does not vary significantly over the course of the year, remaining within 0.3 miles per hour of 4.4 miles per hour throughout.

The predominant average hourly wind direction in Shasta varies throughout the year.

The wind is most often from the south for 2.2 months, from June 28 to September 5, with a peak percentage of 50% on August 5. The wind is most often from the north for 9.8 months, from September 5 to June 28, with a peak percentage of 48% on January 1.

To characterize how pleasant the weather is in Shasta throughout the year, we compute two travel scores.

The tourism score favors clear, rainless days with perceived temperatures between 65°F and 80°F. Based on this score, the best time of year to visit Shasta for general outdoor tourist activities is from mid June to early September, with a peak score in the first week of August.

The beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F. Based on this score, the best time of year to visit Shasta for hot-weather activities is from early July to early August, with a peak score in the third week of July.

Methodology

For each hour between 8:00 AM and 9:00 PM of each day in the analysis period (1980 to 2016), independent scores are computed for perceived temperature, cloud cover, and total precipitation. Those scores are combined into a single hourly composite score, which is then aggregated into days, averaged over all the years in the analysis period, and smoothed.

Our cloud cover score is 10 for fully clear skies, falling linearly to 9 for mostly clear skies, and to 1 for fully overcast skies.

Our precipitation score, which is based on the three-hour precipitation centered on the hour in question, is 10 for no precipitation, falling linearly to 9 for trace precipitation, and to 0 for 0.04 inches of precipitation or more.

Our tourism temperature score is 0 for perceived temperatures below 50°F, rising linearly to 9 for 65°F, to 10 for 75°F, falling linearly to 9 for 80°F, and to 1 for 90°F or hotter.

Our beach/pool temperature score is 0 for perceived temperatures below 65°F, rising linearly to 9 for 75°F, to 10 for 82°F, falling linearly to 9 for 90°F, and to 1 for 100°F or hotter.

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 Shasta typically lasts for 8.1 months (249 days), from around March 12 to around November 16, rarely starting before February 13 or after April 9, and rarely ending before October 29 or after December 3.

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.

Based on growing degree days alone, the first spring blooms in Shasta should appear around February 27, only rarely appearing before February 10 or after March 19.

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 11 to August 23, with an average daily incident shortwave energy per square meter above 7.1 kWh. The brightest month of the year in Shasta is July, with an average of 8.2 kWh.

The darker period of the year lasts for 3.8 months, from October 31 to February 20, with an average daily incident shortwave energy per square meter below 3.1 kWh. The darkest month of the year in Shasta is December, with an average of 1.9 kWh.

For the purposes of this report, the geographical coordinates of Shasta are 40.599 deg latitude, -122.492 deg longitude, and 1,033 ft elevation.

The topography within 2 miles of Shasta contains very significant variations in elevation, with a maximum elevation change of 1,535 feet and an average elevation above sea level of 1,152 feet. Within 10 miles contains very significant variations in elevation (5,745 feet). Within 50 miles also contains extreme variations in elevation (8,806 feet).

The area within 2 miles of Shasta is covered by shrubs (93%), within 10 miles by shrubs (54%) and trees (18%), and within 50 miles by trees (44%) and shrubs (33%).