A consolidated reference for Boston climate: monthly averages, rebuilt from public data on a schedule. Expect -3.5 C at the coldest (Jan) and 22.4 C at the warmest (Jul) — a 25.9 C spread. Expect a wet month and a dry month but no real season: 3.96 mm/day in Oct against 2.59 mm/day in Jan. Taken together that is roughly 1,205 mm of rain a year for the grid cell. Values come from a public open API; a successful result is cached so a later outage never blanks the page. Use the table for exact numbers, or the related pages below for neighbouring locations and periods.
Annual mean temperature 9.6 C
Warmest month Jul (22.4 C)
Coldest month Jan (-3.5 C)
Wettest month Oct (3.96 mm/day)
All-time record high 38.0 C
All-time record low -25.9 C
Annual precipitation 1,208 mm / year
Coordinates 42.35843, -71.05977
Population 653,833
Average monthly temperature and rainfall in Boston
Month
Mean temp (C)
Rain (mm/day)
Record high (C)
Record low (C)
Jan
-3.5
2.59
17.9
-24.3
Feb
-2.6
3.06
18.3
-25.9
Mar
1.3
3.55
23.9
-19.5
Apr
7.4
3.55
30.1
-8.0
May
13.4
3.06
31.6
-0.6
Jun
18.6
3.77
33.8
4.7
Jul
22.4
3.03
36.4
10.1
Aug
22.1
3.01
38.0
10.2
Sep
18.2
3.06
35.9
4.9
Oct
11.5
3.96
30.1
-5.8
Nov
5.3
3.26
22.3
-12.4
Dec
0.0
3.73
19.6
-19.9
What the Boston climate table shows
Values are multi-decadal climatological averages for the 42.35843, -71.05977 grid cell, not a single year. Rain is the daily mean, so a value of 2.00 mm/day is about 60 mm across a 30-day month. Averages smooth over extremes, so use them for planning rather than for what to pack for next Tuesday.
Frequently asked questions
Is Boston climate data a forecast?
No. These are multi-decadal averages for the grid cell, not a prediction for any particular year.
Why do the numbers differ from a weather app?
An app shows one location on one day. These are long-run averages, so they smooth out single hot or cold spells.