Contents
- Weather in September
- Frequently asked questions
- Average temperature in September
- Average pressure in September
- Average wind speed in September
- Average humidity in September
- Average rainfall in September
- Average rainfall days in September
- Average snowfall in September
- Average snowfall days in September
- Average sea temperature in September
- Average daylight in September
- Average sunshine in September
- Average sunshine days in September
- Average UV index in September
- Average cloud cover in September
- Average visibility in September
Weather in September
Temperature
A subtle change in temperatures is noted as August gives way to September, with average highs reducing from a moderately hot 77.7°F (25.4°C) to a pleasant 72°F (22.2°C). Groton reports a consistent average low-temperature of 59.9°F (15.5°C) throughout September nights.Humidity
In Groton, the average relative humidity in September is 78%.Rainfall
The month with the least rainfall is September, when the rain falls for 12 days and typically collects 1.65" (42mm) of precipitation.Snowfall
May through October are months without snowfall.Ocean temperature
In Groton, in September, the average water temperature is 68.2°F (20.1°C).Note: Most people do not enjoy swimming in water of 68.2°F (20.1°C). Breathing control becomes harder as the temperature descends from 69.8°F (21°C) to 59°F (15°C).
Daylight
In September, the average length of the day is 12h and 28min.On the first day of the month, sunrise is at 6:15 am and sunset at 7:20 pm. On the last day of September, sunrise is at 6:44 am and sunset at 6:31 pm EDT.
Sunshine
In Groton, the average sunshine in September is 8.9h.UV index
The average daily maximum UV index in September is 4. A UV Index of 3 to 5 symbolizes a medium health hazard from exposure to the Sun's UV rays for the average person.Note: A maximum high daily UV index of 4 during September translates into the following directions:
Heed the precautions - Protecting the skin and eyes from damage is compulsory. Avoid the Sun's strongest UV rays by seeking shade and limiting exposure during midday. Tightly woven clothing, when worn loosely, shields effectively against the Sun.
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Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the temperature in September?
What is the average humidity in September?
What is the driest month?
How many days does it rain in September in Groton?
When it does not snow?
How cold is the water in September?
What is the average length of the day in September?
What time are sunrise and sunset in September?
How long on average sun shines in September?
What is the UV index intensity in September?
Average temperature in September
Groton, CT
- Average high temperature in September: 72°F
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).
- Average low temperature in September: 59.9°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 in September
Groton, CT
- Average pressure in September: 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 in September
Groton, CT
- Average wind speed in September: 8.8mph
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 in September
Groton, CT
- Average humidity in September: 78%
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 in September
Groton, CT
- Average rainfall in September: 1.65"
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 in September
Groton, CT
- Average rainfall days in September: 12 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 in September
Groton, CT
- Average snowfall in September: 0"
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 in September
Groton, CT
- Average snowfall days in September: 0 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 in September
Groton, CT
- Average sea temperature in September: 68.2°F
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 in September /
Average sunshine in September
Groton, CT
- Average daylight in September: 12h and 3min
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 September: 8h and 5min
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 in September
Groton, CT
- Average sunshine days in September: 15.8 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 in September
Groton, CT
- Average UV index in September: 4
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 in September
Groton, CT
- Average cloud cover in September: 33
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 in September
Groton, CT
- Average visibility in September: 6mi
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).
Groton, Connecticut, USA
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