Weather in Portland in August

Prime time. If you get to pick your dates, August is the one. Highs average 29.9 °C, lows 14.2 °C, and rain falls on 3 days — nothing in the month is working against you.

August ranks 4 of 12 in Portland: past the worst of the year but short of July, which is the month to book if the dates are open.

Rain falls on only 3 days, so an itinerary with no wet-weather fallback is a reasonable risk. Pack for 29.9 °C days and 14.2 °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: 14 days top 30 °C — hot spells arrive, but they break; the day swings 15.6 °C from low to high, which means one bag has to cover both. Across the twenty years measured, the hottest August day reached 41.7 °C and the coldest night fell to 8.2 °C.

This is the volatile part. August rainfall has ranged from 1 mm to 98 mm across the twenty years measured — a 97 mm spread around an average of 19 mm. The average is real but almost no individual August looks like it, so treat the figure as the middle of a wide range rather than a forecast.

Wind is light at 2.7 km/h, so the temperature on the page is close to the temperature on your skin, and humidity is unremarkable at 65%.

How August sits in the year

This is a turning point in the year — July and September sit on opposite sides of it, so the month contains the change rather than following it.

Daylight in August

14.2 hours of daylight, losing 1.4 hours across the month. That is between Portland's extremes of 15.7 and 8.7 hours, so days are long enough not to constrain the plan.

An inland climate

With no coast nearby, the year swings a fair way — 27.7 °C between the warmest afternoons and the coldest nights, wider than any coastal city at this latitude would manage. Within August itself the daily swing is 15.6 °C, so mornings and afternoons need different clothes.

How busy it gets

Peak season. Expect the highest prices of the year and to be booking well ahead.

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

August in Portland versus nearby

If Portland is one option among several, the nearby comparison is worth making. Eugene is a better bet in August — 2.2 °C cooler, 1 day less rain. Seattle is a better bet in August — 6 °C cooler, 2 days more rain.

So: August works, with July the better month by 7 points if the dates can move. If they cannot, nothing here should stop you booking.

Every month in Portland

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