Weather in Tromsø in September

The month to avoid. Of the twelve, September is the one to avoid. Highs sit at 9.5 °C and the day is short; this is an indoors-with-excursions month, not an outdoors-all-day one.

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

Rain on 19 days, 4 of them heavy. Enough to need a plan B, not enough to need a plan around it. Layers, and a genuinely waterproof outer — at 9.5 °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: the day barely swings — 5.2 °C between the overnight low and the afternoon high. Across the twenty years measured, the hottest September day reached 19.3 °C and the coldest night fell to -4.3 °C, and the wettest single day dropped 36 mm — roughly 26% of the month's rain in one day.

September is statistically steady but not small: the year-to-year variation is modest in relative terms, yet the wettest September on record still delivered 238 mm against 24 mm in the driest. In a month this wet, even a tame spread is a lot of rain in absolute terms — the 136 mm average is a reasonable planning figure, not a promise.

Wind is light at 2.8 km/h, so the temperature on the page is close to the temperature on your skin, and humidity runs at 90%, which at 9.5 °C means damp rather than muggy — the kind of cold that gets into a coat and stays there.

How September sits in the year

The month is on the way down: 4.6 °C cooler than August, with October dropping another 6.6 °C. The first week and the last are not the same trip.

Daylight in September

13.5 hours of daylight, losing 4.3 hours across the month. That is between Tromsø's extremes of 24 and 0 hours, so days are long enough not to constrain the plan.

An inland climate

With no coast nearby, the year swings a fair way — 26.3 °C between the warmest afternoons and the coldest nights, wider than any coastal city at this latitude would manage.

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.

September in Tromsø versus nearby

If Tromsø is one option among several, the nearby comparison is worth making. Rovaniemi is a better bet in September — 2.1 °C warmer, 4 days less rain. Umeå is a better bet in September — 4 °C warmer, 6 days less rain.

So: September is a compromise. July is 22 points better and is what Tromsø 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 Tromsø

See all twelve months in Tromsø, or where else to go in September.