Weather in San Antonio in May

Shoulder season. May is shoulder season in San Antonio — cheaper, quieter, and a genuine gamble. Highs average 32.3 °C, lows 19.7 °C, and rain falls on 10 days — nothing in the month is working against you.

May ranks 8 of 12 in San Antonio: past the worst of the year but short of February, which is the month to book if the dates are open.

Rain on 10 days, 3 of them heavy. Enough to need a plan B, not enough to need a plan around it. Pack for 32.3 °C days and 19.7 °C nights; the spread matters more here than any single number.

What the averages hide

Averages flatten a month, and this one hides a few things: 8 days clear 35 °C, so a serious heatwave is normal rather than notable. Across the twenty years measured, the hottest May day reached 41.5 °C and the coldest night fell to 6.6 °C, and the wettest single day dropped 56 mm — roughly 56% of the month's rain in one day.

May is moderately variable: 11 mm in the driest year against 281 mm in the wettest, around an average of 100 mm. Roughly two Mays in three land near that average, and the third does something else entirely.

Wind is light at 11.4 km/h, so the temperature on the page is close to the temperature on your skin, and humidity is unremarkable at 68%.

How May sits in the year

The month is on the way up: 3.2 °C warmer than April, and June adds another 2.9 °C. Late in the month feels noticeably different from the start of it, which is worth knowing if the trip is short.

Daylight in May

May is at or near the longest days of San Antonio's year: 13.6 hours of daylight, gaining 0.6 hours across the month. Evenings are the real gain — dinner outdoors still happens in full light.

An inland climate

With no coast nearby, the year swings a fair way — 31.5 °C between the warmest afternoons and the coldest nights, wider than any coastal city at this latitude would manage.

How busy it gets

Quiet. Few other visitors, cheaper rooms, and a real chance some seasonal operators are shut.

Crowd levels are estimated from climate desirability and school-holiday calendars, not from visitor numbers.

May in San Antonio versus nearby

If San Antonio is one option among several, the nearby comparison is worth making. Corpus Christi is close enough to be a coin toss — within a degree on temperature, 2 days less rain. Laredo is the weaker option in May — 3.3 °C warmer, 2 days less rain.

So: May is a compromise. February is 35 points better and is what San Antonio is actually like at its best — worth moving the trip for if that is possible, and worth adjusting expectations for if it is not.

Every month in San Antonio

See all twelve months in San Antonio, or where else to go in May.