Weather in Brownsville in September

A hard month. September asks something of you. Go in knowing what. You should expect rain on 15 days of the month, which is more days wet than dry.

September ranks 12 of 12 — near the bottom of Brownsville's year. February is the month that works, and the swing between the two is 48 points, which is a different holiday rather than a slightly better one.

Rain on 15 days, 5 of them heavy. Enough to need a plan B, not enough to need a plan around it. Pack for 32.5 °C days and 25 °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: 5 days clear 35 °C, so a serious heatwave is normal rather than notable. Across the twenty years measured, the hottest September day reached 40.3 °C and the coldest night fell to 15.4 °C, and the wettest single day dropped 91 mm — roughly 63% of the month's rain in one day.

September is moderately variable: 14 mm in the driest year against 292 mm in the wettest, around an average of 144 mm. Roughly two Septembers in three land near that average, and the third does something else entirely.

Wind is light at 10.3 km/h, so the temperature on the page is close to the temperature on your skin, and humidity is unremarkable at 74%.

How September sits in the year

The month is on the way down: 2 °C cooler than August, with October dropping another 1.8 °C. The first week and the last are not the same trip. Rain is the thing that moves: October brings 7 days less of it, so pushing the dates later buys drier weather.

Daylight in September

12.3 hours of daylight, losing 0.7 hours across the month. That is between Brownsville's extremes of 13.7 and 10.5 hours, so days are long enough not to constrain the plan.

Sea temperature

The sea sits at about 29.4 °C in September — warm enough that the water offers no relief from the heat. This is the warmest the water gets all year.

How busy it gets

Off season. The genuine off season: cheapest by a distance, with the caveat that some tours and restaurants close entirely.

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

September in Brownsville versus nearby

If Brownsville 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 less rain. Laredo is close enough to be a coin toss — within a degree on temperature, 2 days less rain.

So: September is a compromise. February is 48 points better and is what Brownsville 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 Brownsville

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