Climate Comfort Score
68/100
Good
NOAA 1991–2020 normals 51°F annual avg Public-domain federal data
Groton New London, CT Climate
Annual temperature, rainfall, and a comfort score, sourced from NOAA NCEI's 1991–2020 normals →
- 51°F
- Avg annual temp
- 68/100
- Comfort score
- 39.3"
- Annual precip
- 195d
- Growing season
30-year climate normals from 1 weather station (1991-2020).
The climate verdict for Groton New London
Groton New London, Connecticut averages 51°F a year and scores 68/100 on the comfort index - good, milder than 58% of U.S. cities.
- 51°F
- yearly average temperature, NOAA normal
- 68/100
- comfort score, milder than 58% of U.S. cities
- 39.3"
- precipitation, annual total
- 195 days
- frost-free growing season
Based on NOAA U.S. Climate Normals (1991–2020) - 30-year averages describing the typical year, not a forecast.
Avg Temperature
51°F (11°C)
Avg High
59°F
Avg Low
44°F
Annual Precip
39.3"
Comfort Score
68/100
Good
Avg Annual Temperature
51°F
30-year mean (NOAA NCEI)
Annual Precipitation
39.3"
Liquid-equivalent total
Comfort score vs national 100-point ceiling (Groton New London) 68.0%
National median (63)
PlainClimate composite, temperature mildness, humidity, precipitation, extreme-weather frequency. Good for the Groton New London area.
How Groton New London compares to every U.S. city
Groton New London's comfort score vs. all U.S. cities
PlainClimate composite comfort index (1–100), NOAA 1991–2020 normals
68 Top 42% higher than 58% 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 New London
MethodologyThe chart below traces how the U.S. land temperature anomaly has moved against the global mean since 1900. For Groton New London, 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 | Freeze Days | 90°F+ Days |
|---|---|---|---|---|---|---|
| January | 38°F (3°C) | 23°F (-5°C) | 31°F (-1°C) | 2.7" | 25.2 | 0.0 |
| February | 40°F (5°C) | 25°F (-4°C) | 32°F (0°C) | 2.2" | 23.6 | 0.0 |
| March | 47°F (8°C) | 31°F (-1°C) | 39°F (4°C) | 3.8" | 19.1 | 0.0 |
| April | 56°F (13°C) | 39°F (4°C) | 48°F (9°C) | 3.6" | 5.2 | 0.0 |
| May | 65°F (18°C) | 49°F (9°C) | 57°F (14°C) | 3.3" | 0.2 | 0.0 |
| June | 74°F (23°C) | 58°F (15°C) | 66°F (19°C) | 3.3" | 0.0 | 0.1 |
| July | 80°F (27°C) | 65°F (18°C) | 72°F (22°C) | 3.2" | 0.0 | 1.0 |
| August | 79°F (26°C) | 64°F (18°C) | 72°F (22°C) | 3.3" | 0.0 | 0.6 |
| September | 74°F (23°C) | 57°F (14°C) | 65°F (18°C) | 3.8" | 0.0 | 0.0 |
| October | 63°F (17°C) | 46°F (8°C) | 54°F (12°C) | 3.7" | 1.9 | 0.0 |
| November | 53°F (12°C) | 37°F (3°C) | 45°F (7°C) | 3.2" | 10.4 | 0.0 |
| December | 44°F (7°C) | 29°F (-2°C) | 37°F (3°C) | 3.1" | 21.7 | 0.0 |
Monthly Precipitation
Average monthly rainfall
January 2.7"
8.7 days with precipitation
February 2.2"
7.9 days with precipitation
March 3.8"
9.0 days with precipitation
April 3.6"
10.6 days with precipitation
May 3.3"
12.4 days with precipitation
June 3.3"
10.8 days with precipitation
July 3.2"
9.6 days with precipitation
August 3.3"
9.5 days with precipitation
September 3.8"
8.7 days with precipitation
October 3.7"
9.8 days with precipitation
November 3.2"
8.9 days with precipitation
December 3.1"
10.1 days with precipitation
Frost Dates & Growing Season
First Fall Freeze
October 28
50% probability date
Last Spring Freeze
April 16
50% probability date
Growing Season
195 days
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
5,521
Higher = more heating needed
Cooling Degree Days
608
Higher = more cooling needed
Warmest Month
July
Coldest Month
January
What Groton New London's climate means for you
Groton New London runs 51°F a year - peaking in July, coldest in January.
- Gardeners get about 195 frost-free days, with the last spring freeze near April 16 - plan the planting calendar around it, not the regional average.
- Energy bills track 5,521 heating and 608 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 New London, CT
An annual average temperature of 51°F, ranging from a mean daily high of 59°F to a mean daily low of 44°F is what the NOAA 1991–2020 climate normals report for Groton New London, Connecticut. July is typically the warmest month of the year, while January is the coldest. That baseline comes from station USW00014707 and thirty years of averaging, so it reflects a typical month rather than any one year's swings.
Anyone planning to live, garden, or travel in Groton New London should weigh precipitation alongside temperature: the annual average runs 39.3 inches, predominantly as rainfall. The frost-free season averages 195 days, which directly shapes the planting calendar and growing potential for the area, with the last spring freeze near April 16 and the first fall freeze near October 28. And on the energy front, 5,521 heating degree days and 608 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 New London scores 68/100 (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 New London, CT? ▼
The average annual temperature in Groton New London, Connecticut is 51°F. The warmest month averages 80°F (27°C) and the coldest averages 23°F (-5°C).
How much rain does Groton New London get? ▼
Groton New London receives 39.3 inches of precipitation annually. Based on NOAA 30-year climate normals (1991-2020).
What is the comfort score for Groton New London? ▼
Groton New London has a climate comfort score of 68/100 (Good), milder than 58% of U.S. cities in the PlainClimate database.
When is the growing season in Groton New London? ▼
Groton New London has approximately 195 frost-free days per year, with the last spring freeze around April 16 and the first fall freeze around October 28.
How much energy does heating and cooling require in Groton New London? ▼
Groton New London has 5,521 heating degree days and 608 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 New London climate data come from? ▼
NOAA U.S. Climate Normals v1.0.1 (1991-2020), from weather station USW00014707 near Groton New London.
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). Station: USW00014707. 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.