Chelmsford Weather in September
Average highs run from 81°F on September 1 to 69°F on September 30, and lows from 57°F to 46°F. Normal precipitation for the month is 3.89 in over about 9 wet days.
September day by day
The normal high and low for each date, and the record, in °F.
- Normal low
- Normal high
- Record high
- Record low
September at a glance
- Average high
- 76°F
- Average low
- 52°F
- Precipitation
- 3.89 in
- Record high
- 101°FSep 2, 1953
- Record low
- 28°FSep 25, 1950
- Chance of a freeze
- 11%
- Days of 90°F or more
- 1.3
- Daylight
- 13 h 10 min to 11 h 46 min
- Cloud cover
- 55%
- Humidity
- 75%
- Dew point
- 54°F
- Wind
- 4.7 mph
Every day of the month
A wet day has at least 0.01 inch of precipitation; snow means at least 0.1 inch of snowfall.
| Date | Normal high | Normal low | Record high | Record low | Chance wet | Chance of snow |
|---|---|---|---|---|---|---|
| Sep 1 | 81°F | 57°F | 94°F 1953 | 43°F 2017 | 29% | 0% |
| Sep 2 | 80°F | 56°F | 101°F 1953 | 39°F 2017 | 29% | 0% |
| Sep 3 | 80°F | 56°F | 94°F 2018 | 42°F 2024 | 29% | 0% |
| Sep 4 | 80°F | 56°F | 92°F 1953 | 41°F 1965 | 29% | 0% |
| Sep 5 | 80°F | 55°F | 91°F 2018 | 39°F 1965 | 29% | 0% |
| Sep 6 | 79°F | 55°F | 95°F 2018 | 38°F 2013 | 29% | 0% |
| Sep 7 | 79°F | 55°F | 95°F 2007 | 35°F 1962 | 29% | 0% |
| Sep 8 | 79°F | 55°F | 96°F 2007 | 40°F 1952 | 29% | 0% |
| Sep 9 | 78°F | 54°F | 93°F 2015 | 38°F 2013 | 29% | 0% |
| Sep 10 | 78°F | 54°F | 92°F 2002 | 38°F 2003 | 30% | 0% |
| Sep 11 | 78°F | 53°F | 94°F 2013 | 38°F 1949 | 30% | 0% |
| Sep 12 | 77°F | 53°F | 91°F 1961 | 37°F 1967 | 30% | 0% |
| Sep 13 | 77°F | 53°F | 92°F 1957 | 38°F 1963 | 30% | 0% |
| Sep 14 | 76°F | 52°F | 89°F 2016 | 33°F 1963 | 30% | 0% |
| Sep 15 | 76°F | 52°F | 86°F 2021 | 31°F 1963 | 30% | 0% |
| Sep 16 | 76°F | 52°F | 89°F 2018 | 32°F 1964 | 31% | 0% |
| Sep 17 | 75°F | 51°F | 87°F 2015 | 36°F 2007 | 31% | 0% |
| Sep 18 | 75°F | 51°F | 90°F 1955 | 33°F 2007 | 31% | 0% |
| Sep 19 | 74°F | 50°F | 84°F 1955 | 33°F 2014 | 31% | 0% |
| Sep 20 | 74°F | 50°F | 83°F 1957 | 30°F 1964 | 31% | 0% |
| Sep 21 | 74°F | 50°F | 88°F 1965 | 30°F 2020 | 32% | 0% |
| Sep 22 | 73°F | 49°F | 91°F 1965 | 30°F 1962 | 32% | 0% |
| Sep 23 | 73°F | 49°F | 92°F 2019 | 31°F 1963 | 32% | 0% |
| Sep 24 | 72°F | 48°F | 89°F 2017 | 29°F 1963 | 32% | 0% |
| Sep 25 | 72°F | 48°F | 88°F 1970 | 28°F 1950 | 32% | 0% |
| Sep 26 | 71°F | 47°F | 93°F 2007 | 31°F 1950 | 33% | 0% |
| Sep 27 | 71°F | 47°F | 88°F 2017 | 31°F 1966 | 33% | 0% |
| Sep 28 | 70°F | 47°F | 85°F 2014 | 29°F 1965 | 33% | 0% |
| Sep 29 | 70°F | 46°F | 85°F 1952 | 28°F 2000 | 33% | 0% |
| Sep 30 | 69°F | 46°F | 83°F 1959 | 29°F 1951 | 33% | 0% |
Chance of rain
- Chance of a wet day
- Chance of snowfall
Sunrise and sunset
Times for 2026, local time (EDT).
- September 1
- sunrise 6:10 AM, sunset 7:20 PM
- September 30
- sunrise 6:42 AM, sunset 6:28 PM
Other months
Sources
Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00194313 (Lowell), public domain. Records: NOAA GHCN-Daily, station USW00014702, every year on file, quality-flagged values removed. Cloud, humidity, wind and sunshine: NASA POWER (MERRA-2, CERES and GEWEX SRB), 1991-2020. The data was obtained from the National Aeronautics and Space Administration (NASA) Langley Research Center's Prediction Of Worldwide Energy Resources (POWER) project funded through the NASA Earth Science Division: POWER Daily API v2, accessed 2026-09-24. Sun and moon: computed with the NOAA solar equations and Meeus.