September
Other strong months: June and August
85/100 weather score
United States · 1991–2020
Best time to visit
Somerville
For Somerville, September has the most comfortable weather in our climate comparison. Typical daytime highs are 23°C, nights average 14.6°C, and rainfall totals about 90 mm. Figures use measured 1991–2020 normals from the nearest eligible NOAA station.
Best all-round monthSeptember
Typical daytime high23°C
Typical night-time low14.6°C
September rainfall90 mm
July
Other strong months: August and June
78/100 weather score
May
Other strong months: October and September
82/100 weather score
Make the answer personal
Choose the weather
that suits you.
Set the daytime temperature and rainfall you are comfortable with. We will show only the months that meet every choice, using the measured 1991–2020 averages below.
5 months fit your choices for Somerville
The lowest comfort score is 5 out of 100. January, February, March and December share that score. In January, that is mainly because days reach only 2.9°C, 21° below the 24°C the score treats as ideal.
Quick answers
Planning a trip to Somerville?
These answers come from the same measured monthly climate record shown on this page.
When is the best time to visit Somerville?
September is the strongest all-round choice in our temperature-and-rainfall comparison, with a typical daytime high of 23°C and 90 mm of rain.
What is the hottest month in Somerville?
July is hottest in this record, with a typical daytime high of 28°C and a night-time low of 19°C.
Which month has the least rain?
August has the lowest monthly rainfall total at 80 mm.
Is this a weather forecast?
No. These are long-term measured averages from 1991–2020. Check a current forecast before you travel.
Month by month
See how the weather
changes through the year.
The bars combine daytime temperature, night-time temperature and rainfall. The figures are measured historical averages, not a forecast for a particular trip.
| Month | Day | Night | Rain | Wet days | Sea | Daylight | Comfort | Coverage |
|---|---|---|---|---|---|---|---|---|
| January | 2.9°C | -4.8°C | 86 mm | 8.8 | 4.9°C | 9 h 24 | 5 | Strong coverage |
| February | 4.1°C | -4°C | 82 mm | 8.2 | 3.3°C | 10 h 29 | 5 | Strong coverage |
| March | 7.7°C | -0.4°C | 106 mm | 8.9 | 3.5°C | 11 h 48 | 5 | Strong coverage |
| April | 13.7°C | 4.9°C | 92 mm | 9.1 | 5.8°C | 13 h 18 | 34 | Strong coverage |
| May | 19.3°C | 10.2°C | 83 mm | 9.3 | 10.1°C | 14 h 34 | 64 | Strong coverage |
| June | 24.7°C | 15.5°C | 99 mm | 8.8 | 14.7°C | 15 h 16 | 83 | Strong coverage |
| July | 28°C | 19°C | 83 mm | 7.5 | 18.2°C | 14 h 59 | 69 | Strong coverage |
| August | 27°C | 18.5°C | 80 mm | 7 | 18.8°C | 13 h 54 | 74 | Strong coverage |
| September | 23°C | 14.6°C | 90 mm | 7.1 | 17.0°C | 12 h 26 | 85 | Strong coverage |
| October | 16.9°C | 8.7°C | 102 mm | 7.8 | 13.5°C | 10 h 59 | 51 | Strong coverage |
| November | 11.1°C | 3.4°C | 93 mm | 8.3 | 10.2°C | 9 h 43 | 23 | Strong coverage |
| December | 5.8°C | -1.4°C | 109 mm | 9.4 | 7.5°C | 9 h 05 | 5 | Strong coverage |
What has changed
Recent daytime highs are
0.9°C warmer in Somerville.
Each bar shows the difference between the 2011–2025 average daytime high and the 1961–1990 average for the same month at the same station. A blank month does not have enough older observations for a reliable comparison.
Jan
+1.3
Feb
+1.6
Mar
+0.8
Apr
+0.7
May
+0.5
Jun
0.0
Jul
+0.9
Aug
+0.9
Sep
+1.0
Oct
+0.9
Nov
+0.5
Dec
+1.8
| Month | Record high | Record low | Wettest day | Wettest / driest month | Years |
|---|---|---|---|---|---|
| January | 23.3°C12 Jan 2020 | -24.4°C15 Jan 1957 | 64 mm21 Jan 1979 | 268 mm1979 · driest 16 mm in 1989 | 91 |
| February | 22.8°C24 Feb 2017 | -25.6°C15 Feb 1943 | 68 mm13 Feb 2008 | 202 mm2008 · driest 17 mm in 2024 | 91 |
| March | 31.7°C31 Mar 1998 | -17.2°C5 Mar 1948 | 89 mm18 Mar 1968 | 378 mm2010 · driest 14 mm in 2006 | 91 |
| April | 34.4°C18 Apr 1976 | -8.9°C7 Apr 1982 | 109 mm1 Apr 2004 | 243 mm2004 · driest 21 mm in 1999 | 91 |
| May | 35.6°C19 May 2026 | 1.1°C10 May 2020 | 114 mm16 May 1954 | 340 mm1954 · driest 6 mm in 1944 | 91 |
| June | 38.9°C24 Jun 2025 | 5.0°C1 Jun 1945 | 145 mm13 Jun 1998 | 335 mm1982 · driest 0 mm in 1999 | 91 |
| July | 39.4°C22 Jul 2011 | 10.0°C1 Jul 1988 | 85 mm13 Jul 1996 | 265 mm2023 · driest 13 mm in 1952 | 91 |
| August | 38.9°C2 Aug 1975 | 7.8°C25 Aug 1940 | 179 mm19 Aug 1955 | 434 mm1955 · driest 17 mm in 2007 | 90 |
| September | 37.8°C2 Sep 1953 | 2.8°C27 Sep 1947 | 143 mm11 Sep 1954 | 251 mm1999 · driest 9 mm in 1957 | 90 |
| October | 32.2°C12 Oct 1954 | -3.9°C27 Oct 1936 | 155 mm20 Oct 1996 | 271 mm1996 · driest 9 mm in 1946 | 90 |
| November | 28.3°C2 Nov 1950 | -11.1°C26 Nov 1938 | 84 mm23 Nov 1992 | 235 mm2018 · driest 16 mm in 1976 | 90 |
| December | 24.4°C7 Dec 1998 | -23.9°C20 Dec 1942 | 107 mm12 Dec 1992 | 248 mm1969 · driest 21 mm in 1989 | 90 |
| Month | Days 25°C+ | Days 30°C+ | Frost nights | Heavy rain (10 mm+) | Snow days |
|---|---|---|---|---|---|
| January | 0 | 0 | 25 | 3 | 7 |
| February | 0 | 0 | 22 | 3 | 6 |
| March | <1 | 0 | 16 | 3 | 4 |
| April | 1 | <1 | 2 | 3 | <1 |
| May | 6 | 2 | 0 | 3 | 0 |
| June | 15 | 5 | 0 | 3 | 0 |
| July | 23 | 11 | 0 | 3 | 0 |
| August | 21 | 8 | 0 | 3 | 0 |
| September | 10 | 2 | 0 | 3 | 0 |
| October | 2 | <1 | <1 | 3 | <1 |
| November | <1 | 0 | 7 | 3 | <1 |
| December | 0 | 0 | 20 | 4 | 4 |
The best month has moved. On the 1961–1990 numbers the strongest month here was June (scoring 91); on 2011–2025 it is September (91). Both are scored the same way, from the same station — only the climate underneath changed.
| Month | Dry days reaching 20°C | Wet days | Days with heavy rain | Weeks with 3+ wet days | Typical high by year |
|---|---|---|---|---|---|
| January | <1% | 29% | 11% | 34% | -0.6–5.4°C |
| February | <1% | 29% | 10% | 34% | 1.1–6.6°C |
| March | 3% | 29% | 11% | 36% | 5.1–10.1°C |
| April | 12% | 31% | 10% | 38% | 11.2–15.6°C |
| May | 37% | 30% | 9% | 36% | 17.4–21.6°C |
| June | 63% | 28% | 9% | 31% | 22.5–26.6°C |
| July | 75% | 24% | 8% | 21% | 26.1–29.3°C |
| August | 75% | 24% | 9% | 23% | 25.4–28.3°C |
| September | 57% | 23% | 8% | 21% | 21.3–24.4°C |
| October | 23% | 23% | 9% | 23% | 15.5–19.1°C |
| November | 4% | 28% | 11% | 31% | 9.1–13.4°C |
| December | <1% | 30% | 11% | 36% | 2.8–8.0°C |
A dry day reaching 20°C records under 1 mm of rain. A wet day records at least 1 mm, while a heavy-rain day records at least 10 mm. The weekly figure is the share of seven-day periods containing three or more wet days. The final column shows the middle 80% of average daytime highs recorded for that month in individual years; a wider range means conditions have varied more from one year to another.
The evidence behind this page
Where these figures
come from.
- Place identity
- GeoNames 4951257
- NOAA station
- USW00014739 · BOSTON
- Station distance
- 8 km from the place centre
- Climate period
- 1991–2020
- Minimum month coverage
- 30 usable years
- Daylight
- Calculated from latitude 42.39°, mid-month, sunrise to sunset including refraction. Not a station measurement.
- Sea temperature
- NOAA OISST v2.1 1991–2020 monthly climatology, nearest open water 19 km from the place centre. A sheltered bay can run warmer than the open sea it is measured from.
- Important limit
- Historical climate is not a forecast. Nearby stations can miss mountains, coasts, and local microclimates.
Next step
Choose your month.
Then plan the details.
The weather comparison for Somerville is based on climate evidence, not payments from travel companies. Flight, accommodation and activity links will be clearly labelled when they are added; there are no booking offers on this page today.
How travel partnerships will work