What September feels like in Boston
In Boston, September brings early autumn. Afternoons are warm and pleasant, good for long days out. Once the sun goes down the air changes: nights stay mild. The air is muggy, so it feels hotter than the thermometer suggests.
Rain in Boston in September
Showers are a regular feature, arriving about one day in 3. Rainy days are intense, averaging about 10.2 mm (0.4 in) — downpours rather than drizzle. The yearly figure is similar, around 9.4 mm per wet day.
Daylight and sunshine in September
On 15 September the sun rises at about 6:23 am and sets around 6:56 pm local time, giving 12 h 33 min of daylight. Days are getting shorter: 1 h 24 min less daylight than in mid-August. Measured sunshine covers about 73% of the daylight — there are plenty of bright spells.
How September compares to the rest of the year
Ranked by average high, September comes out as the 4th warmest month in Boston. Compared with August, afternoons are 4°C (7.2°F) cooler, with 6 mm more rain. October is cooler again. The next month's average high: 16.9°C (62.4°F).
Who September suits
- Sightseeing: a good fit — daytime temperatures are fine for walking around.
- Parks & outdoor: a good fit — good conditions for sitting outside.
- Beach: less ideal — too many rainy days.
Tips for visiting Boston in September
Versatile Layers
Mornings and evenings are cooler than midday, so dress in layers.
Rain Protection
A packable rain jacket saves the day on showery afternoons.
Sunglasses
Bright days make sunglasses worth packing.
Quick questions
How warm is Boston in September?
Afternoons average 23.1°C (73.6°F) and nights about 14.6°C (58.3°F) — warm by most people's standards. It is the 4th warmest month of the year.
Does it rain a lot in Boston in September?
It does: about 9 rainy days bring roughly 92 mm, so plan some indoor options.
What should I wear in Boston in September?
The numbers point to versatile layers, rain protection and sunglasses. Bring something extra for the cooler evenings.
Is September or October better for visiting Boston?
On our 12-month climate ranking, September comes out ahead (#1 of 12 vs #3). October is cooler and has more rainy days.