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
| 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).
Rain
| 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.
Sun
| 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.
Humidity
| 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 Time | 12 am | 3 am | 6 am | 9 am | 12 pm | 3 pm | 6 pm | 9 pm |
| Humidity % | 80 | 85 | 87 | 75 | 61 | 53 | 55 | 69 |
Wind
| 9.8 mph | May wind speed average | 15.8 kph |
May is windier than most other months in San Antonio.
Storms
| 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.
Reference
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.