Average Weather in San Francisco Mexico
In San Francisco, the summers are sweltering, the winters are cool, and it is dry and mostly clear year round. Over the course of the year, the temperature typically varies from 51°F to 101°F and is rarely below 46°F or above 106°F.
Based on the tourism score, the best times of year to visit San Francisco for warm-weather activities are from late April to late June and from late September to mid November.
The hot season lasts for 3.6 months, from June 11 to September 29, with an average daily high temperature above 95°F. The hottest day of the year is July 25, with an average high of 101°F and low of 73°F.
The cool season lasts for 3.1 months, from November 24 to February 27, with an average daily high temperature below 79°F. The coldest day of the year is January 7, with an average low of 51°F and high of 75°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
In San Francisco, 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 San Francisco begins around May 1 and lasts for 2.1 months, ending around July 6. On June 11, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 88% of the time, and overcast or mostly cloudy 12% of the time.
The cloudier part of the year begins around July 6 and lasts for 9.9 months, ending around May 1. On July 30, the cloudiest day of the year, the sky is overcast or mostly cloudy 37% of the time, and clear, mostly clear, or partly cloudy 63% of the time.
Cloud Cover Categories
0% clear 20% mostly clear 40% partly cloudy 60% mostly cloudy 80% overcast 100%
San Francisco does not experience significant seasonal variation in the frequency of wet days (i.e., those with greater than 0.04 inches of liquid or liquid-equivalent precipitation). The frequency ranges from 0% to 8%, with an average value of 3%.
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 8% on September 4.
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. San Francisco experiences some seasonal variation in monthly rainfall.
The rainy period of the year lasts for 4.1 months, from August 15 to December 17, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around September 4, with an average total accumulation of 0.7 inches.
The rainless period of the year lasts for 7.9 months, from December 17 to August 15. The least rain falls around May 7, with an average total accumulation of 0.0 inches.
Average Monthly Rainfall
The length of the day in San Francisco varies over the course of the year. In 2020, the shortest day is December 21, with 10 hours, 24 minutes of daylight; the longest day is June 20, with 13 hours, 54 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 6:20 AM on April 4, and the latest sunrise is 1 hour, 19 minutes later at 7:39 AM on October 24. The earliest sunset is at 5:38 PM on November 30, and the latest sunset is 2 hours, 55 minutes later at 8:33 PM on July 1.
Daylight saving time (DST) is observed in San Francisco during 2020, starting in the spring on April 5, lasting 6.6 months, and ending in the fall on October 25.
Sunrise & Sunset with Twilight and Daylight Saving Time
San Francisco experiences some seasonal variation in the perceived humidity.
The muggier period of the year lasts for 2.6 months, from July 18 to October 7, during which time the comfort level is muggy, oppressive, or miserable at least 7% of the time. The muggiest day of the year is September 7, with muggy conditions 29% of the time.
The least muggy day of the year is March 18, when muggy conditions are essentially unheard of.
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 San Francisco experiences significant seasonal variation over the course of the year.
The windier part of the year lasts for 3.7 months, from March 12 to July 3, with average wind speeds of more than 9.2 miles per hour. The windiest day of the year is May 28, with an average hourly wind speed of 10.9 miles per hour.
The calmer time of year lasts for 8.3 months, from July 3 to March 12. The calmest day of the year is August 28, with an average hourly wind speed of 7.5 miles per hour.
Average Wind Speed
The predominant average hourly wind direction in San Francisco varies throughout the year.
The wind is most often from the west for 7.8 months, from February 28 to October 21, with a peak percentage of 88% on May 29. The wind is most often from the north for 4.2 months, from October 21 to February 28, with a peak percentage of 62% on January 1.
San Francisco 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 3.0 months, from July 16 to October 15, with an average temperature above 76°F. The day of the year with the warmest water is September 4, with an average temperature of 79°F.
The time of year with cooler water lasts for 4.7 months, from December 17 to May 7, with an average temperature below 66°F. The day of the year with the coolest water is February 25, with an average temperature of 63°F.
Average Water Temperature
Best Time of Year to Visit
To characterize how pleasant the weather is in San Francisco 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 times of year to visit San Francisco for general outdoor tourist activities are from late April to late June and from late September to mid November, with a peak score in the third week of October.
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 San Francisco for hot-weather activities is from late June to early October, with a peak score in the third 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 San Francisco 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 significant seasonal variation over the course of the year.
The brighter period of the year lasts for 2.9 months, from April 17 to July 12, with an average daily incident shortwave energy per square meter above 7.5 kWh. The brightest day of the year is June 6, with an average of 8.4 kWh.
The darker period of the year lasts for 3.0 months, from November 6 to February 6, with an average daily incident shortwave energy per square meter below 4.8 kWh. The darkest day of the year is December 17, with an average of 3.9 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of San Francisco are 27.645 deg latitude, -113.419 deg longitude, and 243 ft elevation.
The topography within 2 miles of San Francisco is essentially flat, with a maximum elevation change of 59 feet and an average elevation above sea level of 243 feet. Within 10 miles is essentially flat (1,250 feet). Within 50 miles contains very significant variations in elevation (5,217 feet).
The area within 2 miles of San Francisco is covered by shrubs (100%), within 10 miles by shrubs (100%), and within 50 miles by shrubs (90%).
This report illustrates the typical weather in San Francisco, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.
San Francisco is further than 200 kilometers from the nearest reliable weather station, so the weather-related data on this page were taken entirely from NASA's MERRA-2 satellite-era reanalysis . 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.
The temperature and dew point estimates are corrected for the difference between the reference elevation of the MERRA-2 grid cell and the elevation of San Francisco, according to the International Standard Atmosphere .
Time zones for aiports and weather stations are provided by AskGeo.com .