Climate and monthly weather forecastGroton, CT
Climate and monthly weather forecast
The climate of Groton
Groton, Connecticut, USA falls under the Cfb category of the Köppen climate classification; this signifies a marine west coast climate with warm summers. With the Atlantic Ocean influencing the weather, the area experiences relatively mild, damp conditions throughout the year. The geographical location of Groton also plays an integral role in dictating its climate, as it is situated between the highlands and the coast, thereby exposing it to humidity from the sea and cooler air from the land.The yearly temperature in Groton varies quite significantly; monthly average high temperatures range from 36.1°F (2.3°C) in January to 78.6°F (25.9°C) in July, while the average low temperatures fluctuate between a chilly 26.2°F (-3.2°C) in January and a comfortably cool 66.7°F (19.3°C) in July. Relative humidity remains fairly constant throughout the year varying only a few percentage points from a low of 74% to a high of 80% between the months.
Groton also experiences a considerable amount of rainfall and snowfall. There is a broad span of rainfall quantities over the year, with monthly averages ranging from 1.65" (42mm) in September to a high of 3.86" (98mm) in December. Snowfall is predominantly a winter phenomenon, occurring majorly between January, February and March, with January witnessing the maximum average snowfall of 1.81" (46mm).
The best time to visit Groton
With a mild climate that remains comfortable and predictable for the most part of the year, it isn’t hard to pick a suitable time to visit Groton. The high temperatures from June to August peak at a comfortable average of 71.4°F (21.9°C) to 78.6°F (25.9°C), making summer the best time for outdoor activities. Additional amenities of the summer months include lengthy hours of sunshine - about 9.5 to 10.6 per day, high sea temperatures between 69.5°F (20.8°C) to 72.1°F (22.3°C) offering excellent conditions for swimming and other water activities, and lower wind velocities (approximately 7.8mph (12.6km/h)) providing a calming effect.The worst time to visit Groton
The winter months, particularly January and February, can prove to be more difficult for visitors because of the cold conditions. With average high temperatures only reaching between 36.1°F (2.3°C) to 37.9°F (3.3°C) and average lows settling between 26.2°F (-3.2°C) to 27°F (-2.8°C), the weather tends to be quite chilly outside. Despite the low temperatures, the winter months bring a lower amount of daylight, with only 9.2 to 10.6 hours per day in December and January respectively. The significant snowfall during these months could also be potentially detrimental for tourists not accustomed to such conditions.Spring weather in Groton
Spring is a moderate season in Groton, with temperatures gradually rising from an average high of 43.3°F (6.3°C) in March to a more pleasant 63.3°F (17.4°C) by May. Corresponding lows follow a similar pattern, increasing from 32.9°F (0.5°C) to 50.9°F (10.5°C). Rainfall becomes more frequent during this period, with the highest spring average of 3.11" (79mm) occurring in April. Moreover, increasing hours of daylight and relatively lower cloud cover make for a positive change.Summer weather in Groton
The summer months feature comfortable temperatures, ample sunshine, and a little rainfall. The average temperatures fluctuate from a high of 71.4°F (21.9°C) in June to 78.6°F (25.9°C) in July. Rainfall averages range from 2.44" (62mm) to 2.72" (69mm), offering a respite from the intense summer heat. Substantial hours of daylight, roughly between 14.8 to 15.1 hours daily offer a generous amount of time for outdoor activities.Autumn weather in Groton
Autumn in Groton showcases the cooler side of the climate, with the average high temperatures gradually dropping from 72°F (22.2°C) in September to 50.9°F (10.5°C) in November. The lows show a similar pattern, decreasing from 59.9°F (15.5°C) to 40.6°F (4.8°C). Rainfall tends to escalate during this season, reaching its highest in October with an average of 3.39" (86mm).Winter weather in Groton
The winter months in Groton are usually cold and marked by substantial snowfall. Temperatures range from an average high of 36.1°F (2.3°C) in January to 41.9°F (5.5°C) in December, while average lows vary from 26.2°F (-3.2°C) to 33.3°F (0.7°C) within the same time span. The most substantial snowfall of the year takes place in January, with an average of 1.81" (46mm). The winter months are also characterized by shorter daylight hours, ranging from 9.2 to 9.6 hours per day, and the highest relative humidity levels year-round.Weather in January
The first month of the year in Groton, Connecticut is marked by low temperatures and sensible wind conditions. January witnesses a proper winter month with average snowfall being around 1.81" (46mm). The high humidity levels and modest wind flow make the winter chill even more biting. Weather in January »Weather in February
February weather continues the winter trend from January but with slightly higher temperatures and days with snowfall. The month is characterized by mildly increased rainfall and transition of winter into spring. Sea temperatures remain cold, not conducive for maritime activities. Weather in February »Weather in March
The weather in March in Groton, Connecticut, brings a significant transition from winter chills to spring's mild temperatures with lows averaging from 27°F (-2.8°C) in February to 32.9°F (0.5°C). The days get longer, and spring activities commence in full swing. Weather in March »Weather in April
Groton's climate in April witnesses the full bloom of spring season. The month is marked by calm weather with moderate humidity levels. The days of snowfall are almost negligible, and rainfall averages become consistent. The warmer temperatures and extended daylight hours make April pleasant and inviting for tourists and locals alike. Weather in April »Weather in May
Welcome May, the month where Groton's weather becomes warmer, with high temperatures averaging to 63.3°F (17.4°C). The spring season makes way for early summer days as rainfall slightly drops from April. Visually, the city is enveloped in bright, sunlit days with lush green landscapes. Weather in May »Weather in June
June in Groton, Connecticut welcomes the beginning of summer with temperatures becoming warmer and daylight hours considerably longer. Residents anticipate the warm weather, ideal for beach visits and water sports. The city gets busier with summer events and festivities designed to leverage the excellent weather conditions. Weather in June »Weather in July
The heart of summer hits in July, characterized by the highest average temperatures that reach up to 78.6°F (25.9°C). Clear skies, long daylight hours, and enhanced sea temperatures make July the month prime for outdoor and water activities. Weather in July »Weather in August
August carries forward the July warmth with an inconsequential drop in average high temperatures. Groton is in the full swing of the summer season, showcasing clear skies, long sunshine hours, and minimal rain. This climatic pattern makes the city bustling with locals and tourists enjoying the late summer weather. Weather in August »Weather in September
September in Groton is a time of climatic subtlety when summer starts to fade into fall. The weather becomes noticeably cooler, especially during the evening and night hours. The sea temperatures begin to drop, indicating a gradual close to the beach and boating season. Weather in September »Weather in October
The shift to the autumn season is prominent in Groton's weather pattern during October. Average temperatures drop, resulting in cooler nights, signifying the approach of winters. The cityscape turns into varying hues of yellows and browns as leaves start to fall. Weather in October »Weather in November
As November steps in Groton, the city braces itself for winter. The weather turns silver as daylight hours reduce, and rainfall averages increase up to 2.95" (75mm). A complete halt in the beach and boating activities marks the day. Weather in November »Weather in December
Winter takes full form in Groton, Connecticut in December characterized by an average low temperature of 33.3°F (0.7°C). The city experiences a Christmas-like atmosphere with winter intensifying and snowfall likely towards the end of the month. Weather in December »Updated: Aug 1, 2024
Published by: Weather Atlas | About Us
Data Sources | Weather Forecasting & Climate
Published by: Weather Atlas | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
The coldest period tends to be January, when average temperatures fluctuate between a high of 36.1°F (2.3°C) and a low of 26.2°F (-3.2°C).
January, March, April and November, with an average relative humidity of 74%, are the least humid months.
In Groton, during the entire year, the rain falls for 159.8 days and collects up to 33.07" (840mm) of precipitation.
Months with snowfall in Groton are January through April, November and December.
Throughout the year, in Groton, there are 24 snowfall days, and 7.68" (195mm) of snow is accumulated.
January through March, November and December, with an average maximum UV index of 2, are months with the lowest UV index.
With an average ocean temperature of 38.8°F (3.8°C), February is the month with the coldest seawater.
February and December, with an average of 4.9h of sunshine, are months with the least sunshine.
The month with the most snowfall is March, when snow falls for 5.1 days and typically aggregates up to 2.56" (65mm) of snow.
On Sunday, March 10. 2024, at 2:00 am, Daylight Saving Time starts, and the time zone changes from EST to EDT. Daylight Saving Time ends Sunday, November 3. 2024, at 2:00 am, and the time zone reverts from EDT to EST.
In Groton, snow does not fall in May through October.
June is the most humid month, with an average relative humidity of 80%.
June has the longest days of the year, with an average of 15h and 6min of daylight.
The months with the highest UV index are June through August, with an average maximum UV index of 6.
July, characterized by an average high temperature of 78.6°F (25.9°C) and a low temperature of 66.7°F (19.3°C), is generally the warmest month.
With an average ocean temperature of 72.1°F (22.3°C), August is the month with the warmest seawater.
With an average of 10.6h of sunshine, August has the most sunshine of the year.
September is the month with the least rainfall. Rain falls for 12 days and accumulates 1.65" (42mm) of precipitation.
December is the month with the most rainfall. Rain falls for 13.4 days and accumulates 3.86" (98mm) of precipitation.
December has the shortest days of the year, with an average of 9h and 12min of daylight.
Average temperature
Groton, CT
The warmest month (with the highest average high temperature) is July (78.6°F).
The month with the lowest average high temperature is January (36.1°F).
The month with the highest average low temperature is July (66.7°F).
The coldest month (with the lowest average low temperature) is January (26.2°F).
Average pressure
Groton, CT
- Average pressure in January:
30.03"Hg - Average pressure in February:
30.01"Hg - Average pressure in March:
30.04"Hg - Average pressure in April:
29.98"Hg - Average pressure in May:
30.01"Hg - Average pressure in June:
29.93"Hg
- Average pressure in July:
29.95"Hg - Average pressure in August:
29.98"Hg - Average pressure in September:
30.05"Hg - Average pressure in October:
30.01"Hg - Average pressure in November:
30.08"Hg - Average pressure in December:
30.05"Hg
The month with the highest atmospheric pressure is November (30.08"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).
Average wind speed
Groton, CT
- Average wind speed in January:
11.9mph - Average wind speed in February:
11.5mph - Average wind speed in March:
11.4mph - Average wind speed in April:
10.6mph - Average wind speed in May:
9.1mph - Average wind speed in June:
8.1mph
- Average wind speed in July:
7.8mph - Average wind speed in August:
7.8mph - Average wind speed in September:
8.8mph - Average wind speed in October:
10.4mph - Average wind speed in November:
11.1mph - Average wind speed in December:
11.5mph
The windiest month (with the highest average wind speed) is January (11.9mph).
The calmest months (with the lowest average wind speed) are July and August (7.8mph).
Average humidity
Groton, CT
The month with the highest relative humidity is June (80%).
The months with the lowest relative humidity are January, March, April and November (74%).
Average rainfall
Groton, CT
- Average rainfall in January:
2.64" - Average rainfall in February:
2.48" - Average rainfall in March:
2.95" - Average rainfall in April:
3.11" - Average rainfall in May:
2.52" - Average rainfall in June:
2.72"
- Average rainfall in July:
2.44" - Average rainfall in August:
2.36" - Average rainfall in September:
1.65" - Average rainfall in October:
3.39" - Average rainfall in November:
2.95" - Average rainfall in December:
3.86"
The wettest month (with the highest rainfall) is December (3.86").
The driest month (with the least rainfall) is September (1.65").
Average rainfall days
Groton, CT
- Average rainfall days in January:
10.8 days - Average rainfall days in February:
9.5 days - Average rainfall days in March:
13.8 days - Average rainfall days in April:
14.9 days - Average rainfall days in May:
15.6 days - Average rainfall days in June:
15 days
- Average rainfall days in July:
15.8 days - Average rainfall days in August:
13.8 days - Average rainfall days in September:
12 days - Average rainfall days in October:
14.5 days - Average rainfall days in November:
10.7 days - Average rainfall days in December:
13.4 days
The month with the highest number of rainy days is July (15.8 days).
The month with the least rainy days is February (9.5 days).
Average snowfall
Groton, CT
The month with the highest snowfall is March (2.56").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days
Groton, CT
- Average snowfall days in January:
5.9 days - Average snowfall days in February:
6.8 days - Average snowfall days in March:
5.1 days - Average snowfall days in April:
0.7 days - Average snowfall days in May:
0.1 days - Average snowfall days in June:
0 days
- Average snowfall days in July:
0 days - Average snowfall days in August:
0 days - Average snowfall days in September:
0 days - Average snowfall days in October:
0 days - Average snowfall days in November:
0.6 days - Average snowfall days in December:
4.8 days
The month with the highest number of snowfall days is February (6.8 days).
The months with the least snowfall days are June, July, August, September and October (0 days).
Average sea temperature
Groton, CT
The best month for swimming (with the highest average sea temperature) is August (72.1°F).
The coldest month (with the lowest average sea temperature) is February (38.8°F).
Average daylight / Average sunshine
Groton, CT
- Average daylight in January:
9h and 36min - Average daylight in February:
10h and 36min - Average daylight in March:
12h and 0min - Average daylight in April:
13h and 24min - Average daylight in May:
14h and 30min - Average daylight in June:
15h and 6min
- Average daylight in July:
14h and 48min - Average daylight in August:
13h and 48min - Average daylight in September:
12h and 30min - Average daylight in October:
11h and 6min - Average daylight in November:
9h and 54min - Average daylight in December:
9h and 12min
The month with the longest days is June (Average daylight: 15h and 6min).
The month with the shortest days is December (Average daylight: 9h and 12min).
- Average sunshine in January:
5h and 12min - Average sunshine in February:
4h and 54min - Average sunshine in March:
6h and 12min - Average sunshine in April:
8h and 24min - Average sunshine in May:
8h and 36min - Average sunshine in June:
9h and 30min
- Average sunshine in July:
10h and 30min - Average sunshine in August:
10h and 36min - Average sunshine in September:
8h and 54min - Average sunshine in October:
6h and 12min - Average sunshine in November:
5h and 30min - Average sunshine in December:
4h and 54min
The month with the most sunshine is August (Average sunshine: 10h and 36min).
The months with the least sunshine are February and December (Average sunshine: 4h and 54min).
Average sunshine days
Groton, CT
- Average sunshine days in January:
15.1 days - Average sunshine days in February:
12.5 days - Average sunshine days in March:
13.5 days - Average sunshine days in April:
13.8 days - Average sunshine days in May:
13.4 days - Average sunshine days in June:
12.8 days
- Average sunshine days in July:
13.4 days - Average sunshine days in August:
14.6 days - Average sunshine days in September:
15.8 days - Average sunshine days in October:
14.5 days - Average sunshine days in November:
16.5 days - Average sunshine days in December:
13.9 days
The month with the most sunshine days is November (16.5 days).
The month with the least sunshine days is February (12.5 days).
Average UV index
Groton, CT
The months with the highest UV index are June, July and August (UV index 6).
The months with the lowest UV index are January, February, March, November and December (UV index 2).
Average cloud cover
Groton, CT
The months with the most cloud cover are February, March and December (Cloud cover 47).
The month with the least cloud cover is August (Cloud cover 29).
Average visibility
Groton, CT
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
