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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.

Climate Summary

warmhotswelteringhotwarmJanFebMarAprMayJunJulAugSepOctNovDecNowNow88%88%63%63%clearovercastprecipitation: 0.7 inprecipitation: 0.7 in0.0 in0.0 inmuggy: 29%muggy: 29%0%0%drydrytourism score: 7.5tourism score: 7.55.05.0
Click on each chart for more information.

Temperature

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 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 San FranciscoJanFebMarAprMayJunJulAugSepOctNovDec12 AM4 AM8 AM12 PM4 PM8 PM12 AMNowNowcoldcoldcoolcoolcoolcoolwarmwarmhotswelteringcomfortable
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 average hourly temperature, color coded into bands. The shaded overlays indicate night and civil twilight.

Taroudant, Morocco (6,052 miles away) and Minūf, Egypt (7,792 miles) are the far-away foreign places with temperatures most similar to San Francisco (view comparison).

Clouds

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

Cloud Cover Categories in San FranciscoclearercloudiercloudierJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%Jun 1188%Jun 1188%Jul 3063%Jul 3063%May 175%May 175%NowNowclearovercastpartly cloudymostly clearmostly cloudy
0% clear 20% mostly clear 40% partly cloudy 60% mostly cloudy 80% overcast 100%
The percentage of time spent in each cloud cover band, categorized by the percentage of the sky covered by clouds.

Precipitation

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

Daily Chance of Precipitation in San FranciscoJanFebMarAprMayJunJulAugSepOctNovDec0%10%20%30%40%50%60%70%80%90%100%Sep 48%Sep 48%May 190%May 190%Feb 284%Feb 284%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. 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 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 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

Hours of Daylight and Twilight in San FranciscoJanFebMarAprMayJunJulAugSepOctNovDec0 hr24 hr4 hr20 hr8 hr16 hr12 hr12 hr16 hr8 hr20 hr4 hr24 hr0 hr12 hr, 7 minMar 1912 hr, 7 minMar 1913 hr, 54 minJun 2013 hr, 54 minJun 2012 hr, 9 minSep 2212 hr, 9 minSep 2210 hr, 24 minDec 2110 hr, 24 minDec 21nightnightdayNowNow
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 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

Sunrise & Sunset with Twilight and Daylight Saving Time in San FranciscoJanFebMarAprMayJunJulAugSepOctNovDec2 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AMApr 46:20 AMApr 46:20 AM8:33 PMJul 18:33 PMJul 1Nov 305:38 PMNov 305:38 PM7:39 AMOct 247:39 AMOct 24Apr 5DSTApr 5DSTDSTOct 25DSTOct 25daynightnightnightSolarMidnightSolarMidnightSolarNoonSunriseSunset
The solar day over the course of the year 2020. 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.

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

Humidity Comfort Levels in San FranciscomuggyJanFebMarAprMayJunJulAugSepOctNovDec0%10%20%30%40%50%60%70%80%90%100%Mar 180%Mar 180%Sep 729%Sep 729%Jul 187%Jul 187%Oct 77%Oct 77%drydrycomfortablecomfortablemuggymuggy
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
The percentage of time spent at various humidity comfort levels, categorized by dew point.

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 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

Average Wind Speed in San FranciscowindyJanFebMarAprMayJunJulAugSepOctNovDec0 mph2 mph4 mph6 mph8 mph10 mph12 mph14 mphMay 2810.9 mphMay 2810.9 mphAug 287.5 mphAug 287.5 mphMar 129.2 mphMar 129.2 mphNowNow
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 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.

Wind Direction

Wind Direction in San FranciscoNWNJanFebMarAprMayJunJulAugSepOctNovDec0%100%20%80%40%60%60%40%80%20%100%0%NowNowwestnortheastsouth
northeastsouthwest
The percentage of hours in which the mean wind direction is from each of the four cardinal wind directions, excluding hours in which the mean wind speed is less than 1.0 mph. The lightly tinted areas at the boundaries are the percentage of hours spent in the implied intermediate directions (northeast, southeast, southwest, and northwest).

Water Temperature

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

The daily average water temperature (purple line), with 25th to 75th and 10th to 90th percentile bands.

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.

Tourism Score

Tourism Score in San Franciscobest timebest timeJanFebMarAprMayJunJulAugSepOctNovDec02468107.57.55.05.07.27.25.75.7NowNow precipitationprecipitationcloudscloudstourism score
The tourism score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).

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.

Beach/Pool Score

Beach/Pool Score in San Franciscobest timeJanFebMarAprMayJunJulAugSepOctNovDec02468106.76.71.81.8NowNow precipitationprecipitationcloudscloudstemperaturetemperaturebeach/pool score
The beach/pool score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).

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.

Growing Season

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).

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

Time Spent in Various Temperature Bands and the Growing Season in San FranciscoJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%100%Jan 1100%Jan 1100%Jul 2100%Jul 2NowNowcoldcoolwarmhotswelteringcomfortable
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 percentage of time spent in various temperature bands. The black line is the percentage chance that a given day is within the growing season.

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.

Growing Degree Days

Growing Degree Days in San FranciscoJanFebMarAprMayJunJulAugSepOctNovDec0°F1,000°F2,000°F3,000°F4,000°F5,000°F6,000°F7,000°F8,000°FJan 990°FJan 990°FMar 13900°FMar 13900°FMay 21,800°FMay 21,800°FDec 317,668°FDec 317,668°FNowNow
The average growing degree days accumulated over the course of the year, with 25th to 75th and 10th to 90th percentile bands.

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 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

Average Daily Incident Shortwave Solar Energy in San FranciscobrightdarkdarkJanFebMarAprMayJunJulAugSepOctNovDec0 kWh1 kWh2 kWh3 kWh4 kWh5 kWh6 kWh7 kWh8 kWh9 kWhJun 68.4 kWhJun 68.4 kWhDec 173.9 kWhDec 173.9 kWhApr 177.5 kWhApr 177.5 kWhFeb 64.8 kWhFeb 64.8 kWhNowNow
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 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%).

Data Sources

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 .

All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Algorithms 2nd Edition , by Jean Meeus.

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.

We further caution that our travel scores are only as good as the data that underpin them, that weather conditions at any given location and time are unpredictable and variable, and that the definition of the scores reflects a particular set of preferences that may not agree with those of any particular reader.