May weather forecast
San Antonio, TX

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Buildings in San Antonio, Texas, with a calm view of the bridges across the waterfront
Buildings in San Antonio, Texas, with a calm view of the bridges across the waterfront

Weather in May

In May, San Antonio turns noticeably warmer, giving the residents a feel of the upcoming summer heat. Observing the daylight hours extending to 13.6 hours indicates the fast approach of the summer solstice toward the end of June. Yet, despite the increasing temperature, May experiences substantial rainfall, reaching its peak at 3.66in. An increase in humidity radiates an elevated sense of warmth. The generous rainfall and increased sunshine promotes faster-growing flora, adding vibrant colors to the cityscape.

Temperature

May's arrival coincides with a marginal rise in the average high-temperature, moving from April's 79.7°F (26.5°C) to a still warm 85.6°F (29.8°C). Throughout May nights, San Antonio experiences a consistent temperature average of 67.3°F (19.6°C).

Heat index

For May, the heat index is computed to be a sweltering 95°F (35°C). Exercise enhanced safety steps, heat cramps and heat exhaustion are probable. Heatstroke could be a result of sustained activity.
The heat index's values are generally associated with conditions in shade and light breezes. Under direct sunshine, the heat index values might be elevated by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature' or 'feels like', takes into account both air temperature and humidity to illustrate what people actually feel. Elements such as metabolic variations, pregnancy, and physical exertion can influence one's weather perception. Sunshine, when direct, has the potential to intensify weather effects, leading to an increase in the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values are extremely significant for children. Young individuals usually face greater risks than adults as their sweat production is less. Also, their larger skin surface relative to their small bodies and the high heat generation due to their activity contributes to their vulnerability.
The body's inherent cooling system operates through perspiration, wherein evaporating sweat offsets excessive heat. In circumstances of high air temperature and humidity (high heat index), the body's perspiration is restricted, heightening the feeling of warmth. When heat gain surpasses the level the body can shed, body temperature begins to increase, and consequently, overheating and dehydration can occur, with varying severity.

Humidity

With an average relative humidity of 73%, May is the most humid month.

Rainfall

May is the month with the most rainfall. Rain falls for 16.4 days and accumulates 3.66" (93mm) of precipitation.

Snowfall

March through November are months without snowfall.

Daylight

In San Antonio, the average length of the day in May is 13h and 38min.
On the first day of the month, sunrise is at 6:51 am and sunset at 8:10 pm. On the last day of May, sunrise is at 6:34 am and sunset at 8:28 pm CDT.

Sunshine

In May, the average sunshine is 8h.

UV index

The average daily maximum UV index in May is 6. A UV Index estimate of 6 to 7 represents a high health hazard from unsafe exposure to UV radiation for the ordinary person.
Note: In May, a daily UV index of 6 turns into the following recommendations:
Embrace precautions and observe sun safety norms. Evasion of sunburn is a necessity. Stay out of direct sunlight and seek shade between 10 a.m. and 4 p.m., when UV radiation is strongest, but remember that shade devices may not offer full sun protection. Opt for tightly woven and loose clothing to enhance protection from the Sun.
Updated: Jul 14, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

How hot is it in May?

During May, San Antonio experiences an average high-temperature of 85.6°F (29.8°C) and a low-temperature of 67.3°F (19.6°C). In May, the average heat index (a.k.a. 'apparent temperature', 'feels like'), which combines air temperature and relative humidity, is computed to be 95°F (35°C).

What is the most humid month?

May is the most humid month, with an average relative humidity of 73%.

What is the average humidity in May?

The average relative humidity in May is 73%.

What is the wettest month?

The month with the most rainfall is May, when the rain falls for 16.4 days and typically aggregates up to 3.66" (93mm) of precipitation.

How many days does it rain in May?

In San Antonio, in May, during 16.4 rainfall days, 3.66" (93mm) of precipitation is typically accumulated.

When it does not snow in San Antonio?

In San Antonio, snow does not fall in March through November.

What is the average length of the day in May?

In San Antonio, the average day length in May is 13h and 38min.

When are sunrise and sunset in May?

On the first day of May, sunrise is at 6:51 am and sunset at 8:10 pm. On the last day of the month, sunrise is at 6:34 am and sunset at 8:28 pm CDT.

How long on average sun shines in May?

In San Antonio, the average sunshine duration in May is 8h.

What is the UV index reading in May?

In May, the average daily maximum UV index is 6. A UV Index reading of 6 to 7 represents a high hazard to health from unprotected exposure to UV radiation.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in May
San Antonio, TX

Average temperature in May - San Antonio, TX
  • Average high temperature in May: 85.6°F

The warmest month (with the highest average high temperature) is August (96.6°F).
The month with the lowest average high temperature is January (61.7°F).

  • Average low temperature in May: 67.3°F

The month with the highest average low temperature is August (75.7°F).
The coldest month (with the lowest average low temperature) is January (44.2°F).

Average pressure in May
San Antonio, TX

Average pressure in May - San Antonio, TX
  • Average pressure in May: 29.9"Hg

The month with the highest atmospheric pressure is January (30.15"Hg).
The month with the lowest atmospheric pressure is June (29.89"Hg).

Average wind speed in May
San Antonio, TX

Average wind speed in May - San Antonio, TX
  • Average wind speed in May: 9mph

The windiest month (with the highest average wind speed) is May (9mph).
The calmest month (with the lowest average wind speed) is September (6.5mph).

Average humidity in May
San Antonio, TX

Average humidity in May - San Antonio, TX
  • Average humidity in May: 73%

The month with the highest relative humidity is May (73%).
The month with the lowest relative humidity is August (59%).

Average rainfall in May
San Antonio, TX

Average rainfall in May - San Antonio, TX
  • Average rainfall in May: 3.66"

The wettest month (with the highest rainfall) is May (3.66").
The driest month (with the least rainfall) is February (0.98").

Average rainfall days in May
San Antonio, TX

Average rainfall days in May - San Antonio, TX
  • Average rainfall days in May: 16.4 days

The month with the highest number of rainy days is September (17 days).
The month with the least rainy days is January (9.1 days).

Average snowfall in May
San Antonio, TX

Average snowfall in May - San Antonio, TX
  • Average snowfall in May: 0"

The months with the highest snowfall are January and February (0.08").
The months with the least snowfall are March, April, May, June, July, August, September, October and November (0").

Average snowfall days in May
San Antonio, TX

Average snowfall days in May - San Antonio, TX
  • Average snowfall days in May: 0 days

The months with the highest number of snowfall days are January and February (0.3 days).
The months with the least snowfall days are March, April, May, June, July, August, September, October and November (0 days).

Average daylight in May /
Average sunshine in May
San Antonio, TX

Average daylight in May / Average sunshine in May - San Antonio, TX
  • Average daylight in May: 13h and 4min

The month with the longest days is June (Average daylight: 14h and 0min).
The month with the shortest days is December (Average daylight: 10h and 18min).

  • Average sunshine in May: 8h and 0min

The month with the most sunshine is July (Average sunshine: 10h and 18min).
The month with the least sunshine is December (Average sunshine: 5h and 18min).

Average sunshine days in May
San Antonio, TX

Average sunshine days in May - San Antonio, TX
  • Average sunshine days in May: 11.8 days

The month with the most sunshine days is January (20.3 days).
The months with the least sunshine days are May and September (11.8 days).

Average UV index in May
San Antonio, TX

Average UV index in May - San Antonio, TX
  • Average UV index in May: 6

The months with the highest UV index are June, July and August (UV index 7).
The month with the lowest UV index is December (UV index 3).

Average cloud cover in May
San Antonio, TX

Average cloud cover in May - San Antonio, TX
  • Average cloud cover in May: 46

The month with the most cloud cover is March (Cloud cover 47).
The month with the least cloud cover is August (Cloud cover 23).

Average visibility in May
San Antonio, TX

Average visibility in May - San Antonio, TX
  • Average visibility in May: 6mi

The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).

San Antonio, Texas, USA

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