Weather in Las Vegas in September

A hard month. September is a hard month in Las Vegas, and worth planning around. Daytime highs average 36.1 °C and the afternoon is not negotiable — outdoor plans move to early morning or evening.

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

Rain falls on only 2 days, so an itinerary with no wet-weather fallback is a reasonable risk. Pack for heat management rather than style: shade, water, and a schedule that gives up on the middle of the day.

What the averages hide

Averages flatten a month, and this one hides a few things: 20 days of the month clear 35 °C — that is not a heatwave, it is the month. Across the twenty years measured, the hottest September day reached 46.2 °C and the coldest night fell to 9.9 °C.

This is the volatile part. September rainfall has ranged from 0 mm to 27 mm across the twenty years measured — a 27 mm spread around an average of 9 mm. The average is real but almost no individual September looks like it, so treat the figure as the middle of a wide range rather than a forecast.

Wind is light at 8.5 km/h, so the temperature on the page is close to the temperature on your skin, and the air is dry at 23% humidity, which makes the heat far more bearable than the same figure somewhere humid — and dehydrates you faster than you expect.

How September sits in the year

The month is on the way down: 4.1 °C cooler than August, with October dropping another 7.6 °C. The first week and the last are not the same trip.

Daylight in September

12.5 hours of daylight, losing 1.1 hours across the month. That is between Las Vegas's extremes of 14.6 and 9.7 hours, so days are long enough not to constrain the plan.

An inland climate

With no coast nearby, the year swings a fair way — 38.7 °C between the warmest afternoons and the coldest nights, wider than any coastal city at this latitude would manage. Within September itself the daily swing is 14.8 °C, so mornings and afternoons need different clothes.

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 Las Vegas versus nearby

If Las Vegas is one option among several, the nearby comparison is worth making. Riverside is close enough to be a coin toss — within a degree on temperature, 1 day less rain. Sedona is a better bet in September — 5.3 °C cooler, 5 days more rain.

So: September is a compromise. April is 49 points better and is what Las Vegas 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 Las Vegas

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