San Antonio Weather in May

May brings a change in weather to San Antonio, Texas. This month is when the city has its highest humidity and most frequent thunderstorms.

This page gives detailed information on the typical May temperature, precipitation, sun, humidity, wind and storms for San Antonio. The numbers here are historical averages based on climate data gathered at the San Antonio International Airport, located a few miles north of the city center.

Temperature Weather iconTemperature

87 °F May average high 30 °C
66 °F May average low 19 °C
12 days 90 °F max. or more (32 °C)
20 days 70 °F min. or less (21 °C)

The temperature rises nearly every day in May to over 80 degrees Fahrenheit (27 degrees Celsius) in San Antonio. Most years, the temperatures does not get above 100 °F (38 °C) this month.

The thermometer dips to 60 °F (16 °C) or below on an average of 5 nights. May does not normally get as cold as 40 °F (4 °C).

Rainy Weather iconRain

4.4 in total precipitation 112 mm
8 days of rain

Half the time, San Antonio receives 1.8 to 5.7 inches (45 to 145 mm) of rainfall in May. One in four years has drier weather, while another one in four is wetter.

Sunny Weather iconSun

56 % sunshine
6 days clear skies

The sun's rays reach the ground in San Antonio during 56 percent of daylight hours on average in May, for a total of 237 hours in the month. Typically on 6 days this month the sky is mainly clear, with at most 30 percent cloud cover.

Sunlight in May at San Antonio lasts for 13 hours and 38 minutes a day on average. The shortest day of the month is the 1st with 13 hours and 19 minutes of daylight. By the end of the month, the days have lengthened to 13:54 from sunrise to sunset. These durations can vary by a minute or two from year to year.

Humid Weather iconHumidity

71 % May average humidity

This is the most humid time of year for San Antonio. The city's relative humidity during May usually peaks at 87 percent in the morning then drops to 53 percent by mid afternoon.

Local Time12 am3 am6 am9 am12 pm3 pm6 pm9 pm
Humidity % 80 85 87 75 61 53 55 69

Windy Weather iconWind

9.8 mph May wind speed average 15.8 kph

May is windier than most other months in San Antonio.

Stormy Weather iconStorms

3 days rainfall of 0.5 inches (13 mm) or more
7 days with thunderstorms in May

Thunderstorms and heavy rainstorms at San Antonio occur most frequently during May.


The weather data here are long-term averages provided by the US National Centers for Environmental Information (NCEI). Temperature and precipitation are 1991-2020 normals while humidity and thunderstorms are 1961-1990 normals.

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