December weather in Groton, CT
The average temperature in Groton in December is 36.5°F (29.0°F–43.9°F). Average precipitation: 3.13 inches.
December is a winter month in Groton, and is cooler than the annual average of 51.4°F. Daily temperatures swing about 14.9°F between overnight low and afternoon high. Expect about 10 days with precipitation. Daylight averages about 9h 2m. For travel, December is cold.
Avg High
43.9°F
Avg Low
29.0°F
Precipitation
3.13 in
Daylight
9h 2m
December records in Groton
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| December 1 | 66.0°F (2001) | 21.2°F (2019) | 0.87 in (2004) |
| December 2 | 57.9°F (2006) | 16.2°F (2024) | 0.92 in (2018) |
| December 3 | 62.1°F (2009) | 15.1°F (2003) | 1.01 in (2009) |
| December 4 | 57.0°F (2012) | 16.0°F (2000) | 0.15 in (2024) |
| December 5 | 61.0°F (2001) | 12.9°F (2025) | 1.83 in (2020) |
| December 6 | 64.0°F (2001) | 12.9°F (2002) | 0.55 in (2014) |
| December 7 | 60.1°F (2001) | 10.0°F (2002) | 1.49 in (2022) |
| December 8 | 60.1°F (2004) | 14.2°F (2008) | 0.20 in (2001) |
| December 9 | 55.0°F (2019) | 12.9°F (2000) | 1.45 in (2014) |
| December 10 | 60.1°F (2023) | 11.1°F (2010) | 1.10 in (2023) |
| December 11 | 59.0°F (2023) | 18.1°F (2016) | 2.97 in (2024) |
| December 12 | 60.1°F (2008) | 18.1°F (2013) | 1.82 in (2010) |
| December 13 | 60.1°F (2015) | 14.0°F (2005) | 0.91 in (2009) |
| December 14 | 60.1°F (2015) | 10.0°F (2005) | 1.55 in (2019) |
| December 15 | 62.1°F (2015) | 10.0°F (2005) | 0.51 in (2013) |
| December 16 | 57.0°F (2023) | 13.1°F (2016) | 0.90 in (2005) |
| December 17 | 60.1°F (2021) | 14.2°F (2009) | 1.54 in (2000) |
| December 18 | 59.0°F (2023) | 11.1°F (2009) | 2.20 in (2023) |
| December 19 | 55.9°F (2025) | 13.1°F (2011) | 0.42 in (2025) |
| December 20 | 55.9°F (2002) | 6.1°F (2004) | 1.11 in (2002) |
| December 21 | 59.0°F (2018) | 6.1°F (2004) | 0.76 in (2018) |
| December 22 | 62.1°F (2013) | 11.1°F (2024) | 0.71 in (2022) |
| December 23 | 61.0°F (2015) | 7.2°F (2024) | 1.61 in (2015) |
| December 24 | 64.9°F (2015) | 9.1°F (2022) | 0.87 in (2003) |
| December 25 | 62.1°F (2015) | 12.0°F (1999) | 2.06 in (2020) |
| December 26 | 57.9°F (2015) | 10.0°F (2000) | 0.53 in (2005) |
| December 27 | 61.0°F (2016) | 10.9°F (2025) | 0.69 in (2012) |
| December 28 | 55.9°F (2011) | 7.0°F (2025) | 0.98 in (2023) |
| December 29 | 55.0°F (2018) | 7.2°F (2017) | 0.81 in (2013) |
| December 30 | 55.9°F (2022) | 7.2°F (2017) | 1.16 in (2019) |
| December 31 | 55.9°F (2022) | 6.3°F (2017) | 0.78 in (2018) |