Weather in Seattle in May

A good month. May is a solid month to be in Seattle. Highs average 17.8 °C, lows 8.5 °C, and rain falls on 12 days — nothing in the month is working against you.

May ranks 5 of 12 in Seattle: past the worst of the year but short of July, which is the month to book if the dates are open.

Rain on 12 days, 2 of them heavy. Enough to need a plan B, not enough to need a plan around it. Pack for 17.8 °C days and 8.5 °C nights; the spread matters more here than any single number.

What the averages hide

The averages here are honest — no hidden extremes worth planning around. Across the twenty years measured, the hottest May day reached 32.8 °C and the coldest night fell to 0 °C.

May is statistically steady but not small: the year-to-year variation is modest in relative terms, yet the wettest May on record still delivered 118 mm against 21 mm in the driest. In a month this wet, even a tame spread is a lot of rain in absolute terms — the 70 mm average is a reasonable planning figure, not a promise.

Wind is light at 2.2 km/h, so the temperature on the page is close to the temperature on your skin, and humidity runs at 80%, high enough to notice on the warm days without dominating them.

How May sits in the year

The month is on the way up: 4 °C warmer than April, and June adds another 2.3 °C. Late in the month feels noticeably different from the start of it, which is worth knowing if the trip is short. Rain has already shifted: 5 days fewer than April had.

Daylight in May

15.1 hours of daylight, gaining 1.3 hours across the month. That is between Seattle's extremes of 16 and 8.5 hours, so days are long enough not to constrain the plan.

An inland climate

Despite being inland, the year stays fairly even: 21.9 °C between the year's warmest afternoons and coldest nights.

How busy it gets

Shoulder. The value months — prices ease off and you get the place closer to itself.

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

May in Seattle versus nearby

If Seattle is one option among several, the nearby comparison is worth making. Maple Ridge is close enough to be a coin toss — within a degree on temperature, 2 days more rain. Vancouver is close enough to be a coin toss — within a degree on temperature, 3 days more rain.

So: May is a compromise. July is 23 points better and is what Seattle 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 Seattle

See all twelve months in Seattle, or where else to go in May.