San Antonio records about 737mm of rain across roughly 68 wet days a year, which is a 19% chance on an average day. May is the wettest month at 108mm (15% of the annual total) and March the driest at 38mm. Local rain type: thunderstorms. San Antonio gets dramatic spring thunderstorms. The River Walk floods occasionally — check forecasts from April through June.
Chance of rain on an average day: 19%
Rainfall climatology for San Antonio. The live hour-by-hour answer for today loads at the top of this page from Open-Meteo and refreshes through the day — the figures below describe a typical year, not today.
Last updated: · Live forecast data refreshes hourly.
| Annual rainfall | 737mm |
| Rain days per year | 68 |
| Odds on an average day | 19% |
| Wettest month | May — 108mm over 11 days |
| Driest month | March — 38mm over 4 days |
| Rain type | thunderstorms |
| Best dry window | October through December offers dry, comfortable conditions. |
| Worst rain window | May and June bring the heaviest rain as spring thunderstorms. |
May delivers 184% more rain than March (108mm vs 38mm). That gap is the difference between planning around showers and ignoring them.
No single month holds more than 15% of the annual total, so rain in San Antonio is spread through the year — there is no season you can rely on being dry.
San Antonio rain arrives in short, heavy bursts — shelter and timing matter more than gear.
Rain falls on about 11 days in May against 4 in March — the frequency swing matters more for planning than the millimetre totals.
Climate normals. Use them to judge whether today's live forecast at the top of the page is typical or unusual for the season.
| Month | Rainfall | Rain days | Chance on a given day | Highs |
|---|---|---|---|---|
| January | 42mm | 4 | 13% | 16°C |
| February | 42mm | 4 | 13% | 16°C |
| March | 38mm | 4 | 13% | 19°C |
| April | 48mm | 5 | 17% | 23°C |
| May | 108mm | 11 | 37% | 28°C |
| June | 105mm | 10 | 33% | 32°C |
| July | 46mm | 5 | 17% | 35°C |
| August | 48mm | 5 | 17% | 35°C |
| September | 58mm | 6 | 20% | 32°C |
| October | 76mm | 7 | 23% | 28°C |
| November | 42mm | 4 | 13% | 23°C |
| December | 38mm | 4 | 13% | 19°C |
Rain probability is the chance that at least 0.2mm falls at your location — not how long it rains. For San Antonio we combine the hourly probability curve, expected volume in millimetres, and the city's own rainfall record into a single umbrella verdict.
| Factor | Weight | What it measures |
|---|---|---|
| Hourly probability | 40% | Peak and sustained chance of measurable rain across the next 24 hours. |
| Expected volume | 30% | Total millimetres, which separates a passing shower from a genuine soaking. |
| Timing & duration | 20% | When rain starts, when it eases, and the longest continuous dry window. |
| Local rain type | 10% | Drizzle, brief showers, thunderstorms or monsoon — each needs different gear. |
Live hourly values come from Open-Meteo and refresh through the day. Monthly rainfall figures are climate normals, so they describe a typical year rather than a forecast.
San Antonio records rain on roughly 68 days a year — about a 19% chance on any given day — totalling around 737mm.
May, with about 108mm over 11 rain days. That is 15% of the entire year's rainfall in a single month.
March is the driest month at 38mm across roughly 4 days. October through December offers dry, comfortable conditions.
San Antonio gets dramatic spring thunderstorms. The River Walk floods occasionally — check forecasts from April through June.
No. Probability is the chance that at least 0.2mm of rain falls at your location at some point in the period. Check the expected millimetres alongside it: 40% with 0.4mm is a passing shower, 40% with 12mm is a soaking.