Het weer in San Antonio in september

San Antonio forum regulars are consistent that September is still summer and still hot, typical daytime readings “high 80s to 90s°F,” cooling only slightly overnight and not significantly until the early morning hours — genuinely less humid than July or August, but not yet the mild fall the calendar might suggest. Rain is unpredictable and tied to tropical-system remnants: you could see no rain, or it could rain the entire trip, with some visitors recalling rain almost every day, but not all day. The practical advice: skip the coat, keep a light sweater for indoor A/C, and schedule outdoor time around the hottest hours rather than through them. Regulars point to March, April, early May and October as the genuinely mild alternative months. Our record: 33.8°C days, feels-like 36°C, 6.4 rain days and 23.4°C nights — hot with a real chance of rain, matching the “still summer, less humid than peak” read.

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.