Groton (CT) Weather & Climate: Best Time to Visit
Average temperatures, rainfall, sunshine and the best time to visit Groton.
Climate overview of Groton
Groton, Connecticut, United States of America, experiences significant temperature variation throughout the year. Summers bring daytime highs of 27°C (81°F) in July, while winters cool to 4°C (39°F) in January.
The city has a wet climate, receiving around 1244 mm (49 in) of rain/snowfall per year. December is the wettest month. The most sunshine falls in July, with an average of 9.8 hours of daily sunshine.
Groton Weather by Month
Pick a month to see the average temperature, rainfall and sunshine in Groton — and find the best time to visit.
Monthly Temperature in Groton
Depending on the time of the year, temperatures range from comfortable to chilly in Groton. On average, daytime temperatures range from a comfortable 27°C (81°F) in July to a chilly 4°C (39°F) in January.
Nighttime temperatures range from 19°C (66°F) in July to -5°C (23°F) in January.
Check out our detailed temperature page for more information.
Temperature ranges by month
Rainfall in Groton
Groton has a relatively rain/snowy climate with high precipitation levels, averaging 1244 mm (49 in) of rain/snowfall annually. The wettest period in Groton occurs in December, which receives around 128 mm (5 in) of precipitation. During the driest month, November, Groton experiences moderate rainfall, totaling 93 mm (3.7 in). The consistent precipitation levels throughout the year contribute to a relatively stable climate. For more details, please visit our Groton Precipitation page.
The mean monthly precipitation over the year, including rain, hail, and snow
The average number of days each month with precipitation
Sunshine Hours in Groton
In Groton, summer days are longer and more sunny, with daily sunshine hours peaking at 9.8 hours in July. As the darker season arrives, the brightness of the sun becomes less. November sees a soft sun for only 4.6 hours per average day.
Visit our detailed sunshine hours page for more information.
Monthly hours of sunshine
Daily hours of sunshine
Daily percentage of sunshine
Humidity in Groton by Month
The relative humidity is high throughout the year in Groton.
The city experiences its highest humidity in September, reaching 72%. In April, the humidity drops to its lowest level at 58%. What does this mean? Read our detailed page on humidity levels for further details.
Relative humidity over the year
Best Time to Visit Groton
Rainfall during this time ranges from 95 mm (3.7 in) in May to 113 mm (4.4 in) in June. This means you can expect a mix of sunny days and occasional showers. Looking for inspiration on where to travel this year? We have a tool that recommends destinations based on your ideal conditions. Find out where to go with our weather planner.
Frequently asked questions about the climate in Groton
What is the best time to visit Groton?
July and August typically offer the most optimal weather in Groton. In contrast, January, February, March and December tend to have less optimal conditions.
What temperatures can I expect in Groton?
Daytime highs range from 4°C (39°F) in January to 27°C (81°F) in July. Nighttime lows range from -5°C (23°F) to 19°C (66°F). Temperatures vary considerably through the year.
How much rain does Groton get?
Annual rainfall is around 1244 mm (49 in). December is the wettest month with 128 mm (5 in), while November is the driest with 93 mm (3.7 in).
How sunny is Groton?
Groton receives around 2,579 hours of sunshine per year. July is the sunniest month with 293 hours, while November is the cloudiest with just 139 hours. Overall, Groton enjoys abundant sunshine.
Groton 3-Day Forecast
Groton (CT) 3-Day Forecast
Groton on the map
Groton is highlighted — select any city to see its climate.
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