Average Weather in Tamalpais Valley California, United States
In Tamalpais Valley, the summers are long, comfortable, arid, and mostly clear and the winters are short, cold, wet, and partly cloudy. Over the course of the year, the temperature typically varies from 43°F to 72°F and is rarely below 36°F or above 81°F.
Based on the tourism score, the best time of year to visit Tamalpais Valley for warm-weather activities is from late June to early October.
The warm season lasts for 4.3 months, from June 11 to October 22, with an average daily high temperature above 68°F. The hottest day of the year is September 11, with an average high of 72°F and low of 55°F.
The cool season lasts for 2.0 months, from December 3 to February 4, with an average daily high temperature below 58°F. The coldest day of the year is January 1, with an average low of 43°F and high of 54°F.
Average High and Low Temperature
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
Viña del Mar, Chile (5,900 miles away); Millicent, Australia (8,084 miles); and Lakes Entrance, Australia (7,731 miles) are the far-away foreign places with temperatures most similar to Tamalpais Valley (view comparison).
In Tamalpais Valley, 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 Tamalpais Valley begins around May 22 and lasts for 5.0 months, ending around October 23. On July 20, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 92% of the time, and overcast or mostly cloudy 8% of the time.
The cloudier part of the year begins around October 23 and lasts for 7.0 months, ending around May 22. On January 11, the cloudiest day of the year, the sky is overcast or mostly cloudy 55% of the time, and clear, mostly clear, or partly cloudy 45% of the time.
Cloud Cover Categories
0% clear 20% mostly clear 40% partly cloudy 60% mostly cloudy 80% overcast 100%
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Tamalpais Valley varies significantly throughout the year.
The wetter season lasts 5.1 months, from November 4 to April 8, with a greater than 16% chance of a given day being a wet day. The chance of a wet day peaks at 31% on February 20.
The drier season lasts 6.9 months, from April 8 to November 4. The smallest chance of a wet day is 0% on July 19.
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 31% on February 20.
Daily Chance of Precipitation
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. Tamalpais Valley experiences extreme seasonal variation in monthly rainfall.
The rainy period of the year lasts for 7.5 months, from October 3 to May 18, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around February 15, with an average total accumulation of 4.2 inches.
The rainless period of the year lasts for 4.5 months, from May 18 to October 3. The least rain falls around July 31, with an average total accumulation of 0.0 inches.
Average Monthly Rainfall
The length of the day in Tamalpais Valley varies significantly over the course of the year. In 2019, the shortest day is December 21, with 9 hours, 32 minutes of daylight; the longest day is June 21, with 14 hours, 48 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 5:47 AM on June 14, and the latest sunrise is 1 hour, 49 minutes later at 7:36 AM on November 2. The earliest sunset is at 4:50 PM on December 7, and the latest sunset is 3 hours, 46 minutes later at 8:36 PM on June 28.
Daylight saving time (DST) is observed in Tamalpais Valley during 2019, starting in the spring on March 10, lasting 7.8 months, and ending in the fall on November 3.
Sunrise & Sunset with Twilight and Daylight Saving Time
The perceived humidity level in Tamalpais Valley, 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
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
The average hourly wind speed in Tamalpais Valley experiences mild seasonal variation over the course of the year.
The windier part of the year lasts for 5.5 months, from February 2 to July 18, with average wind speeds of more than 8.4 miles per hour. The windiest day of the year is May 31, with an average hourly wind speed of 9.6 miles per hour.
The calmer time of year lasts for 6.4 months, from July 18 to February 2. The calmest day of the year is October 21, with an average hourly wind speed of 7.3 miles per hour.
Average Wind Speed
The predominant average hourly wind direction in Tamalpais Valley varies throughout the year.
The wind is most often from the west for 9.1 months, from February 11 to November 14, with a peak percentage of 93% on August 10. The wind is most often from the north for 2.9 months, from November 14 to February 11, with a peak percentage of 35% on January 1.
Tamalpais Valley is located near a large body of water (e.g., ocean, sea, or large lake). This section reports on the wide-area average surface temperature of that water.
The average water temperature experiences some seasonal variation over the course of the year.
The time of year with warmer water lasts for 2.4 months, from August 7 to October 20, with an average temperature above 57°F. The day of the year with the warmest water is September 16, with an average temperature of 58°F.
The time of year with cooler water lasts for 5.9 months, from December 20 to June 17, with an average temperature below 54°F. The day of the year with the coolest water is May 4, with an average temperature of 53°F.
Average Water Temperature
Best Time of Year to Visit
To characterize how pleasant the weather is in Tamalpais Valley 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 Tamalpais Valley for general outdoor tourist activities is from late June to early October, with a peak score in the first week of September.
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 Tamalpais Valley for hot-weather activities is from late August to late September, with a peak score in the second week of September.
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.
Temperatures in Tamalpais Valley are sufficiently warm year round that it is not entirely meaningful to discuss the growing season in these terms. We nevertheless include the chart below as an illustration of the distribution of temperatures experienced throughout the year.
Time Spent in Various Temperature Bands and the Growing Season
Growing Degree Days
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 3.5 months, from May 7 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 27, with an average of 8.4 kWh.
The darker period of the year lasts for 3.5 months, from November 4 to February 18, with an average daily incident shortwave energy per square meter below 3.4 kWh. The darkest day of the year is December 21, with an average of 2.1 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of Tamalpais Valley are 37.880 deg latitude, -122.546 deg longitude, and 266 ft elevation.
The topography within 2 miles of Tamalpais Valley contains very significant variations in elevation, with a maximum elevation change of 1,010 feet and an average elevation above sea level of 332 feet. Within 10 miles contains very significant variations in elevation (2,569 feet). Within 50 miles contains large variations in elevation (3,789 feet).
The area within 2 miles of Tamalpais Valley is covered by artificial surfaces (35%), trees (28%), and shrubs (22%), within 10 miles by water (52%) and artificial surfaces (18%), and within 50 miles by water (45%) and grassland (18%).
This report illustrates the typical weather in Tamalpais Valley, 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 Tamalpais Valley.
For each station, the records are corrected for the elevation difference between that station and Tamalpais Valley 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 Tamalpais Valley is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Tamalpais Valley and a given station.
The stations contributing to this reconstruction are: Naval Air Station Alameda (historical) (44%, 26 kilometers, southeast); Gnoss Field (36%, 30 kilometers, north); and Buchanan Field Airport (20%, 45 kilometers, east).
Time zones for aiports and weather stations are provided by AskGeo.com .