Groton climate

Groton Weather in September

NOAA 1991-2020 normals for Andover #2, 15.5 km from Groton

Average highs run from 78°F on September 1 to 66°F on September 30, and lows from 56°F to 44°F. Normal precipitation for the month is 2.47 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
73°F
Average low
50°F
Precipitation
2.47 in
Record high
97°FSep 16, 2018
Record low
24°FSep 23, 2012
Chance of a freeze
33%
Days of 90°F or more
1.4
Daylight
13 h 16 min to 11 h 44 min
Cloud cover
52%
Humidity
61%
Dew point
47°F
Wind
11.2 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 178°F56°F93°F 201249°F 20240%
Sep 277°F55°F90°F 201247°F 20140%
Sep 377°F55°F95°F 202644°F 20250%
Sep 477°F55°F94°F 202339°F 20250%
Sep 576°F54°F92°F 202640°F 20250%
Sep 676°F54°F85°F 202137°F 20170%
Sep 776°F54°F88°F 202236°F 20250%
Sep 876°F53°F89°F 202238°F 20120%
Sep 975°F53°F84°F 202431°F 20200%
Sep 1075°F53°F94°F 201231°F 20200%
Sep 1175°F52°F94°F 201838°F 20200%
Sep 1274°F52°F94°F 201734°F 20140%
Sep 1374°F52°F91°F 201733°F 20120%
Sep 1473°F51°F89°F 202232°F 20140%
Sep 1573°F51°F91°F 201231°F 20110%
Sep 1673°F50°F97°F 201834°F 2014
Sep 1772°F50°F85°F 201932°F 2017
Sep 1872°F50°F85°F 201630°F 2012
Sep 1971°F49°F88°F 202333°F 2015
Sep 2071°F49°F84°F 201944°F 2024
Sep 2171°F48°F91°F 201536°F 2012
Sep 2270°F48°F91°F 201730°F 2012
Sep 2370°F47°F82°F 202124°F 2012
Sep 2469°F47°F82°F 201231°F 2012
Sep 2569°F47°F85°F 201431°F 2021
Sep 2668°F46°F87°F 202134°F 2018
Sep 2768°F46°F86°F 202136°F 2017
Sep 2867°F45°F91°F 202130°F 2018
Sep 2967°F45°F88°F 202430°F 2018
Sep 3066°F44°F86°F 201236°F 2011

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 (CDT).

September 1
sunrise 6:54 AM, sunset 8:10 PM
September 30
sunrise 7:30 AM, sunset 7:14 PM

Every day of September: sun and moon

Other months

Sources

Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00390120 (Andover #2), public domain. Records: NOAA GHCN-Daily, station USC00390022, 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 2026-09-25. Sun and moon: computed with the NOAA solar equations and Meeus.