Weather in Seattle in March

A hard month. March is a hard month in Seattle, and worth planning around. You should expect rain on 20 days of the month, which is more days wet than dry.

March ranks 8 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 20 of the month's 31 days, 4 of them heavy. At that frequency a wet-weather backup is not a contingency, it is the itinerary — book the indoor things first and treat the clear days as the bonus. Layers, and a genuinely waterproof outer — at 11 °C the difference between a good day and a miserable one is entirely down to what you are wearing.

What the averages hide

Averages flatten a month, and this one hides a few things: 3 nights fall below freezing. Across the twenty years measured, the hottest March day reached 22.1 °C and the coldest night fell to -3.6 °C, and the wettest single day dropped 42 mm — roughly 30% of the month's rain in one day.

March is statistically steady but not small: the year-to-year variation is modest in relative terms, yet the wettest March on record still delivered 260 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 138 mm average is a reasonable planning figure, not a promise.

Wind is light at 3.1 km/h, so the temperature on the page is close to the temperature on your skin, and humidity runs at 85%, which at 11 °C means damp rather than muggy — the kind of cold that gets into a coat and stays there.

How March sits in the year

The month is on the way up: 2.3 °C warmer than February, and April adds another 2.8 °C. Late in the month feels noticeably different from the start of it, which is worth knowing if the trip is short.

Daylight in March

11.8 hours of daylight, gaining 1.7 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

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.

March 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, 1 day more rain. Vancouver is the weaker option in March — 3.9 °C cooler, the same number of rain days.

So: March is a compromise. July is 58 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 March.