Climate Comfort Score
63/100
Good
NOAA 1991–2020 normals 52°F annual avg Public-domain federal data
- 52°F
- Avg annual temp
- 63/100
- Comfort score
- 48.9"
- Annual precip
- 208d
- Growing season
30-year climate normals from 1 weather station (1991-2020).
The climate verdict for Groton
Groton, Connecticut averages 52°F a year and scores 63/100 on the comfort index - good, milder than 47% of U.S. cities.
- 52°F
- average temperature, NOAA 1991-2020 normal
- 63/100
- comfort score, milder than 47% of U.S. cities
- 48.9"
- annual precipitation · 25" snow
- 208 days
- growing season, frost-free days
Based on NOAA U.S. Climate Normals (1991–2020) - 30-year averages describing the typical year, not a forecast.
Avg Temperature
52°F (11°C)
Avg High
60°F
Avg Low
45°F
Annual Precip
48.9"
Annual Snow
24.5"
Comfort Score
63/100
Good
Avg Annual Temperature
52°F
30-year mean (NOAA NCEI)
Annual Precipitation
48.9"
Plus 24.5" of snow
Comfort score vs national 100-point ceiling (Groton) 63.0%
National median (63)
PlainClimate composite, temperature mildness, humidity, precipitation, extreme-weather frequency. Good for the Groton area.
How Groton compares to every U.S. city
Groton's comfort score vs. all U.S. cities
PlainClimate composite comfort index (1–100), NOAA 1991–2020 normals
63 Top 53% higher than 47% of 6,915 US cities
Each bar is a band; taller bars hold more US cities. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count, share, and where it sits relative to this entry.
Source NOAA U.S. Climate Normals, PlainClimate comfort index · 1991–2020
Warming context for Groton
MethodologyThe chart below traces how the U.S. land temperature anomaly has moved against the global mean since 1900. For Groton, the NOAA 1991-2020 normal captures average conditions across that spread - notably, the most recent decade runs warmer than the 30-year mean itself.
- United States land mean (NOAA NCEI) +0.11 °C/decade
- Global anomaly (NASA GISTEMP) +0.11 °C/decade
- Paris Agreement thresholds 1.5°C / 2.0°C
Monthly Temperatures
Average daily high and low temperatures by month
| Month | Avg High | Avg Low | Mean | Precip | Snow | Freeze Days | 90°F+ Days |
|---|---|---|---|---|---|---|---|
| January | 39°F (4°C) | 24°F (-5°C) | 31°F (0°C) | 3.9" | 5.8" | 25.5 | 0.0 |
| February | 41°F (5°C) | 25°F (-4°C) | 33°F (0°C) | 3.4" | 8.3" | 22.6 | 0.0 |
| March | 47°F (8°C) | 32°F (0°C) | 40°F (4°C) | 4.9" | 3.9" | 17.7 | 0.0 |
| April | 57°F (14°C) | 41°F (5°C) | 49°F (9°C) | 4.4" | 0.8" | 4.1 | 0.0 |
| May | 66°F (19°C) | 50°F (10°C) | 58°F (15°C) | 3.7" | 0.0" | 0.0 | 0.0 |
| June | 75°F (24°C) | 59°F (15°C) | 67°F (20°C) | 3.9" | 0.0" | 0.0 | 0.4 |
| July | 81°F (27°C) | 66°F (19°C) | 73°F (23°C) | 3.4" | 0.0" | 0.0 | 1.8 |
| August | 80°F (27°C) | 65°F (18°C) | 73°F (23°C) | 4.2" | 0.0" | 0.0 | 0.7 |
| September | 74°F (23°C) | 58°F (14°C) | 66°F (19°C) | 4.3" | 0.0" | 0.0 | 0.1 |
| October | 63°F (17°C) | 47°F (8°C) | 55°F (13°C) | 4.4" | 0.0" | 1.1 | 0.0 |
| November | 53°F (12°C) | 38°F (3°C) | 46°F (8°C) | 3.8" | 0.5" | 9.5 | 0.0 |
| December | 44°F (7°C) | 30°F (-1°C) | 37°F (3°C) | 4.6" | 5.2" | 20.9 | 0.0 |
Monthly Precipitation
Average monthly rainfall and snowfall
January 3.9"
Snow: 5.8"
11.4 days with precipitation
February 3.4"
Snow: 8.3"
9.7 days with precipitation
March 4.9"
Snow: 3.9"
11.5 days with precipitation
April 4.4"
Snow: 0.8"
11.6 days with precipitation
May 3.7"
11.9 days with precipitation
June 3.9"
9.5 days with precipitation
July 3.4"
9.7 days with precipitation
August 4.2"
9.3 days with precipitation
September 4.3"
10.2 days with precipitation
October 4.4"
10.4 days with precipitation
November 3.8"
Snow: 0.5"
10.0 days with precipitation
December 4.6"
Snow: 5.2"
12.4 days with precipitation
Frost Dates & Growing Season
First Fall Freeze
November 2
50% probability date
Last Spring Freeze
April 8
50% probability date
Growing Season
208 days
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
5,333
Higher = more heating needed
Cooling Degree Days
721
Higher = more cooling needed
Warmest Month
July
Coldest Month
January
What Groton's climate means for you
Groton runs 52°F a year - peaking in July, coldest in January.
- Gardeners get about 208 frost-free days, with the last spring freeze near April 8 - plan the planting calendar around it, not the regional average.
- Energy bills track 5,333 heating and 721 cooling degree days a year, higher means the furnace or AC runs more.
- Comparing places to live? Line this city up against nearby cities and the national rankings. See rankings
These are 30-year NOAA normals (1991–2020) - the typical year, not a forecast for any specific season.
Climate Guides
Climate Insight: Groton, CT
In Groton, Connecticut, the NOAA 1991–2020 climate normals put the annual average temperature at 52°F, ranging from a mean daily high of 60°F to a mean daily low of 45°F. July is typically the warmest month of the year, while January is the coldest. As thirty-year averages computed from station USC00063207, these numbers smooth out year-to-year noise into a working baseline for a typical month.
Beyond temperature, Groton averages 48.9 inches of precipitation annually, with 24.5 inches typically falling as snow - a real factor for anyone planning to live, garden, or travel here. The frost-free season averages 208 days, which directly shapes the planting calendar and growing potential for the area, with the last spring freeze near April 8 and the first fall freeze near November 2. Turning to energy use, 5,333 heating degree days and 721 cooling degree days tell the story of how often furnaces and air conditioners run during a normal year.
On PlainClimate's composite comfort index, Groton scores 63/100 (Good), a blended measure that weighs temperature mildness, precipitation moderation, and extreme-weather frequency against one another. Use the monthly tables above to plan around specific windows, shoulder seasons for mild highs and lows, peak summer for July-driven heat, or deep winter for January-driven cold. All figures here are thirty-year averages: any single year may run warmer, wetter, drier, or cooler than the normal, so treat them as planning guidance rather than forecasts.
Frequently Asked Questions
What is the average temperature in Groton, CT? ▼
The average annual temperature in Groton, Connecticut is 52°F. The warmest month averages 81°F (27°C) and the coldest averages 24°F (-5°C).
How much rain does Groton get? ▼
Groton receives 48.9 inches of precipitation annually, including 24.5 inches of snow. Based on NOAA 30-year climate normals (1991-2020).
What is the comfort score for Groton? ▼
Groton has a climate comfort score of 63/100 (Good), milder than 47% of U.S. cities in the PlainClimate database.
When is the growing season in Groton? ▼
Groton has approximately 208 frost-free days per year, with the last spring freeze around April 8 and the first fall freeze around November 2.
How much energy does heating and cooling require in Groton? ▼
Groton has 5,333 heating degree days and 721 cooling degree days annually, a heating-dominated climate. See our <a href="/guides/reading-weather-data/" class="underline hover:text-brand-600">guide to reading weather data</a> for what these figures mean.
Where does this Groton climate data come from? ▼
NOAA U.S. Climate Normals v1.0.1 (1991-2020), from weather station USC00063207 near Groton.
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). Station: USC00063207. For informational purposes only.
Read our methodology - how this data is sourced, computed, and verified.
Related
Data sourced from official public datasets. See our methodology for details. Retrieved and formatted by PlainClimate Editorial
Every figure on PlainClimate is rendered directly from NOAA 1991-2020 U.S. Climate Normals data, no number is typed in by an editor. This page draws directly on NOAA 1991-2020 U.S. Climate Normals data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.