Weather in Hermosillo in August

The month to avoid. August is the month most people should skip in Hermosillo. Daytime highs average 36.8 °C and the afternoon is not negotiable — outdoor plans move to early morning or evening.

August ranks 11 of 12 — near the bottom of Hermosillo's year. December is the month that works, and the swing between the two is 74 points, which is a different holiday rather than a slightly better one.

Rain on 14 days, 3 of them heavy. Enough to need a plan B, not enough to need a plan around it. 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: 21 days of the month clear 35 °C — that is not a heatwave, it is the month. Across the twenty years measured, the hottest August day reached 46.1 °C and the coldest night fell to 20.7 °C, and the wettest single day dropped 55 mm — roughly 56% of the month's rain in one day.

August is statistically steady but not small: the year-to-year variation is modest in relative terms, yet the wettest August on record still delivered 145 mm against 33 mm in the driest. In a month this wet, even a tame spread is a lot of rain in absolute terms — the 98 mm average is a reasonable planning figure, not a promise.

Wind is light at 7 km/h, so the temperature on the page is close to the temperature on your skin, and humidity is unremarkable at 60%.

How August sits in the year

Temperatures hold steady either side: 37.4 °C in July, 36.8 here, 36.3 in September. Nothing about the timing within the month matters much. Rain is the thing that moves: September brings 5 days less of it, so pushing the dates later buys drier weather.

Daylight in August

13.2 hours of daylight, losing 0.7 hours across the month. That is between Hermosillo's extremes of 14 and 10.3 hours, so days are long enough not to constrain the plan.

An inland climate

With no coast nearby, the year swings a fair way — 30.1 °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.

August in Hermosillo versus nearby

If Hermosillo is one option among several, the nearby comparison is worth making. Tucson is close enough to be a coin toss — within a degree on temperature, 2 days more rain. Chihuahua is a better bet in August — 5.6 °C cooler, 2 days more rain.

So: August is a compromise. December is 69 points better and is what Hermosillo 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 Hermosillo

See all twelve months in Hermosillo, or where else to go in August.