Weather in Niigata in September

A good month. September works. It is not the peak, but nothing about it fights you. You should expect rain on 15 days of the month, which is more days wet than dry.

September ranks 3 of 12 in Niigata. Only June scores clearly higher, and the difference is small enough to be settled by price rather than weather.

Rain on 15 days, 5 of them heavy. Enough to need a plan B, not enough to need a plan around it. Nothing specialised needed — this is the month you pack for the trip rather than for the weather.

What the averages hide

Averages flatten a month, and this one hides a few things: the day barely swings — 2.8 °C between the overnight low and the afternoon high. Across the twenty years measured, the hottest September day reached 31.7 °C and the coldest night fell to 15.7 °C, and the wettest single day dropped 79 mm — roughly 56% of the month's rain in one day.

September is moderately variable: 40 mm in the driest year against 307 mm in the wettest, around an average of 141 mm. Roughly two Septembers in three land near that average, and the third does something else entirely.

Wind is light at 12.1 km/h, so the temperature on the page is close to the temperature on your skin, and humidity runs at 76%, 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 °C cooler than August, with October dropping another 5.1 °C. The first week and the last are not the same trip.

Daylight in September

12.5 hours of daylight, losing 1.2 hours across the month. That is between Niigata's extremes of 14.8 and 9.6 hours, so days are long enough not to constrain the plan.

Sea temperature

The sea sits at about 24.7 °C in September — warm enough to stay in as long as you like. This is the warmest the water gets all year.

How busy it gets

Busy. Popular without being frantic; book the things you care about, improvise the rest.

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

September in Niigata versus nearby

If Niigata is one option among several, the nearby comparison is worth making. Sendai is close enough to be a coin toss — within a degree on temperature, 1 day more rain. Utsunomiya is close enough to be a coin toss — 2.1 °C warmer, the same number of rain days.

So: September works, with June the better month by 8 points if the dates can move. If they cannot, nothing here should stop you booking.

Every month in Niigata

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