Monthly Climate
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Best time to visit Boston

September is the best time to visit Boston for general sightseeing, with average highs of 23 °C and about 8 wet days. The comfortable season runs roughly August to September.

It depends what you are going for

One month rarely wins on everything. These are the best months on each measure taken on its own.

If you want Best month On that measure
Sightseeing and walking September comfort 90/100
A beach holiday August sea 19 °C
The least cloud September 52 % average cloud cover
The least rain July 74 mm
Warmth July 28 °C
Cooler weather January 1.9 °C

Ranked by comfort

# Month Comfort / 100 Avg high Wet days Beach
1 September 90 23 °C 8 56
2 June 85 24 °C 10 48
3 August 80 27 °C 9 70
4 May 80 19 °C 11 26
5 July 77 28 °C 9 67
6 October 71 16 °C 10 19
7 April 56 14 °C 11 9
8 November 45 10 °C 10 11
9 March 30 7.1 °C 10 10
10 February 29 3.3 °C 9 13
11 January 27 1.9 °C 10 11
12 December 26 4.8 °C 10 10

For a beach holiday

August scores highest, with a sea temperature of 19 °C and air temperatures around 27 °C. The sea never reaches 20 °C here.

Month Sea Air Sunshine Beach score
January 4.9 °C 1.9 °C 57 % 11
February 3.3 °C 3.3 °C 57 % 13
March 3.5 °C 7.1 °C 60 % 10
April 5.8 °C 14 °C 61 % 9
May 10 °C 19 °C 63 % 26
June 15 °C 24 °C 60 % 48
July 18 °C 28 °C 55 % 67
August 19 °C 27 °C 52 % 70
September 17 °C 23 °C 52 % 56
October 14 °C 16 °C 53 % 19
November 10 °C 10 °C 56 % 11
December 7.5 °C 4.8 °C 58 % 10

When to think twice

December scores lowest with about 10 wet days and highs near 4.8 °C. That does not make it a bad month — it depends entirely on what you are travelling for. The numbers are all here; the judgement is yours.

The full year

Month Avg high Rainfall Cloud
January 1.9 °C 93 mm 57 %
February 3.3 °C 83 mm 57 %
March 7.1 °C 116 mm 60 %
April 13.5 °C 101 mm 61 %
May 19.1 °C 80 mm 63 %
June 24.4 °C 88 mm 60 %
July 27.8 °C 74 mm 55 %
August 26.9 °C 86 mm 52 %
September 22.7 °C 90 mm 52 %
October 16.3 °C 108 mm 53 %
November 10.2 °C 94 mm 56 %
December 4.8 °C 116 mm 58 %

Data sources and method

Normal period
1991–2020
Dataset version
era5-1991-2020-scores1.1
Last processed

Measured values come from ERA5 reanalysis and are reproduced unchanged. Calculated by us: comfort score, beach score, season boundaries. Full formulas are on the methodology page.

Contains modified Copernicus Climate Change Service information 2026. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.