Weather in Porto Alegre in August

A good month. August works. It is not the peak, but nothing about it fights you. Highs average 20.6 °C, lows 10.4 °C, and rain falls on 11 days — nothing in the month is working against you.

August ranks 3 of 12 in Porto Alegre. Only April scores clearly higher, and the difference is small enough to be settled by price rather than weather.

Rain on 11 days, 4 of them heavy. Enough to need a plan B, not enough to need a plan around it. Nothing specialised needed — this is the month you pack for the trip rather than for the weather.

What the averages hide

Averages flatten a month, and this one hides a few things: it never really gets hot: not one day in an average August reaches 30 °C. Across the twenty years measured, the hottest August day reached 30.6 °C and the coldest night fell to 0.8 °C, and the wettest single day dropped 59 mm — roughly 51% of the month's rain in one day.

August is moderately variable: 45 mm in the driest year against 246 mm in the wettest, around an average of 116 mm. Roughly two Augusts in three land near that average, and the third does something else entirely.

Wind is light at 8 km/h, so the temperature on the page is close to the temperature on your skin, and humidity runs at 85%, high enough to notice on the warm days without dominating them.

How August sits in the year

Temperatures hold steady either side: 18.8 °C in July, 20.6 here, 21.9 in September. Nothing about the timing within the month matters much.

Daylight in August

11 hours of daylight, gaining 0.8 hours across the month. That is between Porto Alegre's extremes of 14.1 and 10.2 hours, so days are long enough not to constrain the plan.

Sea temperature

The sea sits at about 16.5 °C in August — cold — a quick dip rather than a swim, and a wetsuit if you are in for longer. The sea peaks at 25.3 °C in February and bottoms out at 16.5 °C — water lags the air by a month or two, which is why the best swimming often comes after the best weather.

How busy it gets

Peak season. Expect the highest prices of the year and to be booking well ahead. If the dates are flexible, September is the trade worth considering — 6 points weaker on weather, and materially quieter.

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

August in Porto Alegre versus nearby

If Porto Alegre is one option among several, the nearby comparison is worth making. Curitiba is close enough to be a coin toss — within a degree on temperature, 3 days less rain. São Paulo is a better bet in August — 4 °C warmer, 4 days less rain.

So: August is effectively as good as it gets here — 1 points behind April, which is inside the margin where the weather stops being the deciding factor and price starts being it.

Every month in Porto Alegre

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