Weather in Monterrey in September

A hard month. September is a hard month in Monterrey, and worth planning around. You should expect rain on 16 days of the month, which is more days wet than dry.

September ranks 8 of 12 in Monterrey: past the worst of the year but short of January, which is the month to book if the dates are open.

Rain on 16 days, 4 of them heavy. Enough to need a plan B, not enough to need a plan around it. Pack for 32.9 °C days and 21.6 °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: 7 days clear 35 °C, so a serious heatwave is normal rather than notable. Across the twenty years measured, the hottest September day reached 40.1 °C and the coldest night fell to 14 °C, and the wettest single day dropped 124 mm — roughly 94% of the month's rain in one day.

September is moderately variable: 20 mm in the driest year against 224 mm in the wettest, around an average of 132 mm. Roughly two Septembers in three land near that average, and the third does something else entirely.

Wind is light at 8.3 km/h, so the temperature on the page is close to the temperature on your skin, and humidity is unremarkable at 73%.

How September sits in the year

Temperatures hold steady either side: 36 °C in August, 32.9 here, 32.1 in October. Nothing about the timing within the month matters much. Rain is the thing that moves: October brings 8 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 Monterrey's extremes of 13.7 and 10.5 hours, so days are long enough not to constrain the plan.

An inland climate

With no coast nearby, the year swings a fair way — 25.7 °C between the warmest afternoons and the coldest nights, wider than any coastal city at this latitude would manage.

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 Monterrey versus nearby

If Monterrey is one option among several, the nearby comparison is worth making. Laredo is close enough to be a coin toss — within a degree on temperature, 3 days less rain. Brownsville is close enough to be a coin toss — within a degree on temperature, 1 day less rain.

So: September is a compromise. January is 52 points better and is what Monterrey 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 Monterrey

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