San Antonio weather in May
May in San Antonio: sweltering, rainy — a great time to visit.
Updated September 2026 · climate normals from ERA5 reanalysis
#8 of 12 months in San Antonio · #1038 of 1413 destinations to visit in May · comfort 70/100 (tier B)
- Days
- 32°C
- Nights
- 21°C
- Wet days
- 8
- Sun
- 10.2 h
- Humidity
- 72%
- Daylight
- 14 h

Traveller notes on San Antonio in May
Other months in San Antonio
Regulars are blunt that Texas weather doesn't make up its mind until close to the trip itself, with swings from the upper 70s one day to the upper 30s just two days later well within normal range for this month. Our row backs the mild average sitting between those extremes, 20.7C over 7.3C nights feeling 5C, with 47.6mm of rain across 4.6 days. Regulars are consistent the standard packing answer is simply everything - shorts and short sleeves for a warm afternoon, a real jacket for a cold snap - checking the forecast close to departure rather than trusting any single seasonal average. Snow is essentially a non-issue here, regulars call it a rare novelty rather than a planning concern. Visiting after Thanksgiving means catching the River Walk's holiday lights, a genuine seasonal highlight regulars are quick to recommend. The record: humidity 69 percent, 6.4 hours of sun, a 17.1 kph wind and AQI 31.
Regulars call this the best stretch of the year here, past the nasty summer highs but still genuinely shorts weather right up to around Halloween, with the caveat that an incoming cold front can swing a given day anywhere from the 40s to the 90s Fahrenheit. Our row backs the warm-but-cooling read, 29.3C reading as 30C over 16.5C nights, with 54.3mm of rain across 4.9 days. Regulars specifically steer outdoor-pool plans toward September instead, since by this point a cold front can make an afternoon swim genuinely too chilly to enjoy even on an otherwise warm-looking day. The record: humidity 63 percent, 9.3 hours of sun, a 16.3 kph wind and one of the cleanest air readings in this project, AQI 37.
March and April are the two months regulars name for this city - flowers and trees in bloom, wildflowers at their best in late March and early April, and weather they call perfect - and then they cut the month in half. The last two weeks are Fiesta, a city-wide event drawing something like two and a half million people, and the Riverwalk sidewalks are congested throughout it. Anyone who dislikes crowds books the first fortnight; anyone who came for the event books the second. The Riverwalk itself stays shaded and comfortable year-round. Our row: 28C days over 15.5C nights, 72mm across 5.8 days, 8.9 hours of sun and a 20.2 kph wind.
November is the month San Antonio regulars call perfect - sunny, pleasant, the trees turning, and mornings in the low 50s Fahrenheit warming into the middle and upper 70s. Our row's 22.5C day over a 10.2C night is that spread. They rate it above mid-September and above early October, which can still be genuinely hot. The caveat is the standing Texas one: the month can equally deliver 40s, so layers and a jacket for the early morning and the evening. The other November note is the calendar - the holiday lights go on in the middle of the month, and several regulars push visitors one month further to early December for the same weather plus the full display. The record: 5 precipitation days carrying 42.1mm, humidity 69 percent and 7.1 hours of sun.
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San Antonio climate normals — May
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
Crowds in San Antonio in May
How busy the place itself is — school and mass holidays, the months an editor tagged, and how sought-after the weather makes them. Never part of the comfort score.
Shoulder seasonan ordinary month(estimated)
Peak crowdsBusyShoulder seasonQuiet
Best months for San Antonio's weather
Ranked by this destination's own climate comfort score across the year — a different thing from how busy it gets (see Crowds above).
Fair weatherSan Antonio's best weather comes in March, April and November — separate windows, not one continuous season.
Best weatherFair weatherToughest weather
What's on in San Antonio in May
Recurring seasonal events, natural spectacles, closures and holidays — curated and sourced.
- Hazard
Flash flood season
1 May – 15 Jun · usuallyThe Hill Country upstream turns rain into wall-of-water floods faster than almost anywhere in the country, and late spring is the worst of it. Low crossings close; the city's tunnels handle the rest. Source ↗
Nearby, and something's on
Within 300 km of San Antonio — a day trip or a short hop — with something on this month. Never part of the comfort score.
Where is San Antonio?
San Antonio in May — FAQ
- Is May a good time to visit San Antonio?
- May in San Antonio: sweltering, rainy — a great time to visit. It ranks #8 of 12 months for San Antonio on SeasonMap's comfort score (70/100).
- What is the weather like in San Antonio in May?
- In May, San Antonio averages a daily high of 31.5°C and a low of 20.5°C, with about 95.9 mm of rain over roughly 8.1 rainy days.
- What is the air quality in San Antonio in May?
- San Antonio has a mean US Air Quality Index of about 52 in May.
Within 300 km: Austin's Congress Avenue bats around 20 Mar – 1 Nov.