Weather in Perth in August

A good month. August is a solid month to be in Perth. Highs average 17.6 °C, lows 13.3 °C, and rain falls on 14 days — nothing in the month is working against you.

August ranks 11 of 12 — near the bottom of Perth's year. January is the month that works, and the swing between the two is 34 points, which is a different holiday rather than a slightly better one. Worth keeping in perspective: August is the weakest month of Perth's year and it is still a perfectly good one. The downside here is small.

Rain on 14 days, 4 of them heavy. Enough to need a plan B, not enough to need a plan around it. Pack for 17.6 °C days and 13.3 °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: the day barely swings — 4.2 °C between the overnight low and the afternoon high. Across the twenty years measured, the hottest August day reached 24 °C and the coldest night fell to 8.3 °C, and the wettest single day dropped 40 mm — roughly 38% 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 168 mm against 28 mm in the driest. In a month this wet, even a tame spread is a lot of rain in absolute terms — the 106 mm average is a reasonable planning figure, not a promise.

Wind sits around 17.9 km/h — a steady breeze rather than a nuisance, and welcome on the warmer days, and humidity is unremarkable at 74%.

How August sits in the year

Temperatures hold steady either side: 17.6 °C in July, 17.6 here, 18 in September. Nothing about the timing within the month matters much.

Daylight in August

10.9 hours of daylight, gaining 0.8 hours across the month. That is between Perth's extremes of 14.2 and 10.1 hours, so days are long enough not to constrain the plan.

Sea temperature

The sea sits at about 19.7 °C in August — swimmable, but it takes a moment to commit. The sea peaks at 22.9 °C in March and bottoms out at 19 °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

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.

August in Perth versus nearby

If Perth is one option among several, the nearby comparison is worth making. Bunbury is close enough to be a coin toss — within a degree on temperature, 1 day more rain. Geraldton is a better bet in August — within a degree on temperature, 4 days less rain.

So: August is a compromise. January is 33 points better and is what Perth 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 Perth

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