Weather in Gdańsk in September

A good month. September is a solid month to be in Gdańsk. Highs average 17.9 °C, lows 12.5 °C, and rain falls on 12 days — nothing in the month is working against you.

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

Rain on 12 days, 1 of them heavy. Enough to need a plan B, not enough to need a plan around it. Pack for 17.9 °C days and 12.5 °C nights; the spread matters more here than any single number.

What the averages hide

Averages flatten a month, and this one hides a few things: the day barely swings — 5.4 °C between the overnight low and the afternoon high. Across the twenty years measured, the hottest September day reached 27.9 °C and the coldest night fell to 5.9 °C, and the wettest single day dropped 27 mm — roughly 43% of the month's rain in one day.

September is moderately variable: 27 mm in the driest year against 131 mm in the wettest, around an average of 63 mm. Roughly two Septembers in three land near that average, and the third does something else entirely.

Wind is light at 15.7 km/h, so the temperature on the page is close to the temperature on your skin, and humidity runs at 79%, high enough to notice on the warm days without dominating them.

How September sits in the year

The month is on the way down: 3.7 °C cooler than August, with October dropping another 5.5 °C. The first week and the last are not the same trip.

Daylight in September

12.8 hours of daylight, losing 2.2 hours across the month. That is between Gdańsk's extremes of 17.2 and 7.4 hours, so days are long enough not to constrain the plan.

Sea temperature

The sea sits at about 16.5 °C in September — cold — a quick dip rather than a swim, and a wetsuit if you are in for longer. This is the warmest the water gets all year.

How busy it gets

Peak season. Expect the highest prices of the year and to be booking well ahead.

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

September in Gdańsk versus nearby

If Gdańsk is one option among several, the nearby comparison is worth making. Warsaw is a better bet in September — 2.5 °C warmer, 2 days less rain. Szczecin is close enough to be a coin toss — within a degree on temperature, 2 days less rain.

So: September is effectively as good as it gets here — 3 points behind August, which is inside the margin where the weather stops being the deciding factor and price starts being it.

Every month in Gdańsk

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