Weather in Boston in March

The month to avoid. March is the month most people should skip in Boston. Highs sit at 6.4 °C and the day is short; this is an indoors-with-excursions month, not an outdoors-all-day one.

March ranks 9 of 12 in Boston: past the worst of the year but short of September, which is the month to book if the dates are open.

Rain on 10 days, 3 of them heavy. Enough to need a plan B, not enough to need a plan around it. Layers, and a genuinely waterproof outer — at 6.4 °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: 23 nights drop below freezing, so anything left outside stays frozen. Across the twenty years measured, the hottest March day reached 24.3 °C and the coldest night fell to -19.1 °C, and the wettest single day dropped 92 mm — roughly 84% of the month's rain in one day.

March is moderately variable: 16 mm in the driest year against 349 mm in the wettest, around an average of 110 mm. Roughly two Marchs in three land near that average, and the third does something else entirely.

Wind is light at 3.7 km/h, so the temperature on the page is close to the temperature on your skin, and humidity runs at 82%, which at 6.4 °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: 4.4 °C warmer than February, and April adds another 6.8 °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

11.9 hours of daylight, gaining 1.4 hours across the month. That is between Boston's extremes of 15.3 and 9.1 hours, so days are long enough not to constrain the plan.

Sea temperature

The sea sits at about 4.6 °C in March — too cold to swim without a wetsuit. The sea peaks at 19.7 °C in August and bottoms out at 4.6 °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.

March in Boston versus nearby

If Boston is one option among several, the nearby comparison is worth making. New York City is close enough to be a coin toss — within a degree on temperature, the same number of rain days. Bar Harbor is close enough to be a coin toss — 3 °C cooler, the same number of rain days.

So: March is a compromise. September is 49 points better and is what Boston 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 Boston

See all twelve months in Boston, or where else to go in March.