Average Weather in San Antonio Texas, United States
In San Antonio, the summers are hot and oppressive, the winters are short and cool, and it is partly cloudy year round. Over the course of the year, the temperature typically varies from 43°F to 96°F and is rarely below 31°F or above 101°F.
The hot season lasts for 3.7 months, from May 29 to September 20, with an average daily high temperature above 89°F. The hottest day of the year is August 6, with an average high of 96°F and low of 76°F.
The cool season lasts for 2.8 months, from November 26 to February 21, with an average daily high temperature below 70°F. The coldest day of the year is January 6, with an average low of 43°F and high of 63°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 Antonio, the average percentage of the sky covered by clouds experiences mild seasonal variation over the course of the year.
The clearer part of the year in San Antonio begins around May 5 and lasts for 2.0 months, ending around July 5. On June 11, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 73% of the time, and overcast or mostly cloudy 27% of the time.
The cloudier part of the year begins around July 5 and lasts for 10 months, ending around May 5. On January 3, the cloudiest day of the year, the sky is overcast or mostly cloudy 46% of the time, and clear, mostly clear, or partly cloudy 54% 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 San Antonio varies throughout the year.
The wetter season lasts 5.9 months, from April 27 to October 24, with a greater than 22% chance of a given day being a wet day. The chance of a wet day peaks at 31% on May 21.
The drier season lasts 6.1 months, from October 24 to April 27. The smallest chance of a wet day is 13% on December 16.
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 May 21.
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 Antonio experiences significant seasonal variation in monthly rainfall.
Rain falls throughout the year in San Antonio. The most rain falls during the 31 days centered around May 25, with an average total accumulation of 3.6 inches.
The least rain falls around August 1, with an average total accumulation of 1.4 inches.
Average Monthly Rainfall
The length of the day in San Antonio varies significantly over the course of the year. In 2017, the shortest day is December 21, with 10 hours, 16 minutes of daylight; the longest day is June 21, with 14 hours, 2 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 6:33 AM on June 10, and the latest sunrise is 1 hour, 16 minutes later at 7:49 AM on November 4. The earliest sunset is at 5:34 PM on November 30, and the latest sunset is 3 hours, 3 minutes later at 8:37 PM on June 30.
Daylight saving time (DST) is observed in San Antonio 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
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 Antonio experiences extreme seasonal variation in the perceived humidity.
The muggier period of the year lasts for 6.7 months, from April 9 to October 31, during which time the comfort level is muggy, oppressive, or miserable at least 24% of the time. The muggiest day of the year is July 1, with muggy conditions 89% of the time.
The least muggy day of the year is January 23, with muggy conditions 2% of the time.
Humidity Comfort Levels
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 Antonio experiences mild seasonal variation over the course of the year.
The windier part of the year lasts for 5.9 months, from January 18 to July 16, with average wind speeds of more than 4.9 miles per hour. The windiest day of the year is April 2, with an average hourly wind speed of 5.6 miles per hour.
The calmer time of year lasts for 6.1 months, from July 16 to January 18. The calmest day of the year is September 5, with an average hourly wind speed of 4.3 miles per hour.
Average Wind Speed
The predominant average hourly wind direction in San Antonio varies throughout the year.
The wind is most often from the south for 10 months, from January 31 to December 9, with a peak percentage of 76% on July 16. The wind is most often from the north for 1.7 months, from December 9 to January 31, with a peak percentage of 39% on January 1.
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 4.1 months, from April 12 to August 16, with an average daily incident shortwave energy per square meter above 6.2 kWh. The brightest day of the year is June 14, with an average of 7.0 kWh.
The darker period of the year lasts for 2.8 months, from November 11 to February 4, with an average daily incident shortwave energy per square meter below 4.0 kWh. The darkest day of the year is December 19, with an average of 3.2 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of San Antonio are 29.424 deg latitude, -98.494 deg longitude, and 663 ft elevation.
The topography within 2 miles of San Antonio contains only modest variations in elevation, with a maximum elevation change of 151 feet and an average elevation above sea level of 657 feet. Within 10 miles contains only modest variations in elevation (577 feet). Within 50 miles contains significant variations in elevation (1,831 feet).
The area within 2 miles of San Antonio is covered by artificial surfaces (100%), within 10 miles by artificial surfaces (65%) and shrubs (23%), and within 50 miles by shrubs (38%) and cropland (25%).
This report illustrates the typical weather in San Antonio, 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 San Antonio.
For each station, the records are corrected for the elevation difference between that station and San Antonio 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 San Antonio is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between San Antonio and a given station.
The stations contributing to this reconstruction are: Stinson Municipal Airport (38%, 10 kilometers, south); Kelly Field Annex (39%, 10 kilometers, southwest); and San Antonio International Airport (23%, 13 kilometers, north).
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.