Groton climate

Groton Weather in September

NOAA 1991-2020 normals for Nashua Cwsu, 15.7 km from Groton

Average highs run from 80°F on September 1 to 69°F on September 30, and lows from 57°F to 46°F. Normal precipitation for the month is 4.15 in.

September day by day

The normal high and low for each date, and the record, in °F.

Normal daily high and low temperature at Groton, in °F, with the record for each date.20406080100151015202530
  • Normal low
  • Normal high
  • Record high
  • Record low

September at a glance

Average high
75°F
Average low
52°F
Precipitation
4.15 in
Record high
96°FSep 8, 2015
Record low
28°FSep 29, 2000
Chance of a freeze
14%
Days of 90°F or more
3.0
Daylight
13 h 09 min to 11 h 47 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.

DateNormal highNormal lowRecord highRecord lowChance wetChance of snow
Sep 180°F57°F94°F 201045°F 20090%
Sep 280°F57°F95°F 201044°F 20010%
Sep 380°F57°F91°F 199946°F 20240%
Sep 480°F57°F89°F 200849°F 20070%
Sep 579°F56°F91°F 202345°F 20070%
Sep 679°F56°F93°F 202342°F 20130%
Sep 779°F56°F94°F 202346°F 20090%
Sep 878°F55°F96°F 201545°F 20130%
Sep 978°F55°F94°F 200242°F 20130%
Sep 1078°F55°F91°F 200244°F 20030%
Sep 1177°F54°F96°F 201343°F 20050%
Sep 1277°F54°F90°F 200540°F 20060%
Sep 1377°F54°F88°F 200542°F 20190%
Sep 1476°F53°F88°F 200541°F 20190%
Sep 1576°F53°F85°F 201739°F 20010%
Sep 1675°F52°F88°F 201540°F 20070%
Sep 1775°F52°F87°F 201536°F 20130%
Sep 1875°F52°F86°F 201538°F 20070%
Sep 1974°F51°F82°F 201336°F 20190%
Sep 2074°F51°F86°F 199834°F 20200%
Sep 2173°F50°F85°F 201932°F 20200%
Sep 2273°F50°F87°F 201633°F 20200%
Sep 2372°F49°F90°F 201938°F 20140%
Sep 2472°F49°F90°F 201737°F 19980%
Sep 2571°F48°F90°F 201737°F 20120%
Sep 2671°F48°F91°F 200736°F 20090%
Sep 2770°F47°F90°F 201736°F 20150%
Sep 2870°F47°F86°F 201432°F 20000%
Sep 2970°F46°F84°F 201528°F 20000%
Sep 3069°F46°F78°F 201532°F 20000%

Chance of rain

The chance of at least 0.01 inch of precipitation on each date at Groton, in percent, and of at least 0.1 inch of snowfall.00.21102030
  • Chance of a wet day
  • Chance of snowfall

Sunrise and sunset

Times for 2026, local time (EDT).

September 1
sunrise 6:11 AM, sunset 7:20 PM
September 30
sunrise 6:42 AM, sunset 6:29 PM

Every day of September: sun and moon

Other months

Sources

Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00275703 (Nashua Cwsu), public domain. Records: NOAA GHCN-Daily, station USW00004780, 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.