Weather in Thunder Bay in March

The month to avoid. Of the twelve, March is the one to avoid. Highs sit at 0.6 °C and the day is short; this is an indoors-with-excursions month, not an outdoors-all-day one.

March ranks 11 of 12 — near the bottom of Thunder Bay's year. August is the month that works, and the swing between the two is 54 points, which is a different holiday rather than a slightly better one.

Rain on 7 days, 0 of them heavy. Enough to need a plan B, not enough to need a plan around it. Layers, and a genuinely waterproof outer — at 0.6 °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: 29 nights drop below freezing, so anything left outside stays frozen. Across the twenty years measured, the hottest March day reached 21.7 °C and the coldest night fell to -28.3 °C.

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 68 mm against 8 mm in the driest. In a month this wet, even a tame spread is a lot of rain in absolute terms — the 30 mm average is a reasonable planning figure, not a promise.

Wind is light at 4.6 km/h, so the temperature on the page is close to the temperature on your skin, and humidity runs at 85%, which at 0.6 °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: 8 °C warmer than February, and April adds another 8.4 °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 1.8 hours across the month. That is between Thunder Bay's extremes of 16.1 and 8.4 hours, so days are long enough not to constrain the plan.

An inland climate

Thunder Bay has no sea to moderate it, and it shows: 42 °C separates the hottest afternoon of the year from the coldest night. That is a genuinely continental range, and it means summer and winter here are barely the same place.

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 Thunder Bay versus nearby

If Thunder Bay is one option among several, the nearby comparison is worth making. Minneapolis is close enough to be a coin toss — 4.7 °C warmer, the same number of rain days. Milwaukee is close enough to be a coin toss — 5.6 °C warmer, 2 days more rain.

So: March is a compromise. August is 52 points better and is what Thunder Bay 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 Thunder Bay

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