Weather in Houston in September

Shoulder season. September sits in between. You will get good days and you will lose some. Highs average 32.2 °C, lows 21.8 °C, and rain falls on 13 days — nothing in the month is working against you.

September ranks 9 of 12 in Houston: past the worst of the year but short of March, which is the month to book if the dates are open.

Rain on 13 days, 3 of them heavy. Enough to need a plan B, not enough to need a plan around it. Pack for 32.2 °C days and 21.8 °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: 6 days clear 35 °C, so a serious heatwave is normal rather than notable. Across the twenty years measured, the hottest September day reached 41 °C and the coldest night fell to 10.7 °C, and the wettest single day dropped 128 mm — roughly 108% of the month's rain in one day.

September is statistically steady but not small: the year-to-year variation is modest in relative terms, yet the wettest September on record still delivered 194 mm against 36 mm in the driest. In a month this wet, even a tame spread is a lot of rain in absolute terms — the 118 mm average is a reasonable planning figure, not a promise.

Wind is light at 5.5 km/h, so the temperature on the page is close to the temperature on your skin, and humidity runs at 75%, high enough to notice on the warm days without dominating them.

How September sits in the year

The month is on the way down: 3 °C cooler than August, with October dropping another 4 °C. The first week and the last are not the same trip.

Daylight in September

12.4 hours of daylight, losing 0.9 hours across the month. That is between Houston's extremes of 14 and 10.2 hours, so days are long enough not to constrain the plan.

An inland climate

With no coast nearby, the year swings a fair way — 30 °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.

September in Houston versus nearby

If Houston 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, 1 day more rain. San Antonio is close enough to be a coin toss — within a degree on temperature, 3 days less rain.

So: September is a compromise. March is 31 points better and is what Houston 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 Houston

See all twelve months in Houston, or where else to go in September.