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
Chatham's September reports an average high-temperature of an enjoyable 66.6°F (19.2°C), exhibiting a minor difference from August. Chatham's September nights experience a subtle temperature dip to an average of 63.3°F (17.4°C).Humidity
In September, the average relative humidity is 80%.Rainfall
In Chatham, Massachusetts, in September, during 10.7 rainfall days, 1.85" (47mm) of precipitation is typically accumulated. In Chatham, during the entire year, the rain falls for 142.4 days and collects up to 22.09" (561mm) of precipitation.Snowfall
In Chatham, Massachusetts, snow does not fall in May through October.Ocean temperature
In Chatham, in September, the average water temperature is 63.9°F (17.7°C).Note: Swimming in water at 63.9°F (17.7°C) is not a pleasing experience for the majority. As the temperature descends from 69.8°F (21°C) to 59°F (15°C), controlling breathing becomes increasingly hard.
Daylight
In September, the average length of the day is 12h and 28min.On the first day of September in Chatham, sunrise is at 6:06 am and sunset at 7:12 pm. On the last day of the month, sunrise is at 6:36 am and sunset at 6:22 pm EDT.
Sunshine
In September, the average sunshine is 8.5h.UV index
The average daily maximum UV index in September is 4. A UV Index of 3 to 5 symbolizes a moderate threat to health from exposure to the Sun's UV radiation for the average person.Note: In September, the maximum UV index of 4 transforms into these recommendations:
Take measures. Individuals with light skin might experience burns in under 30 minutes. Around midday, solar radiation is most harmful; hence, exposure should be limited. For a sun-safe wardrobe, go for clothes that are tightly woven and generously sized.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the usual temperature for Chatham in September?
What is the average humidity in September?
How many days does it rain in September?
When it does not snow?
What is the ocean temperature in September?
What is the average length of the day in September?
When is the sunrise / sunset in September?
How many hours of sunshine does Chatham have in September?
What is the UV index intensity in September?
Average temperature in September
Chatham, MA
- Average high temperature in September: 66.6°F
The warmest month (with the highest average high temperature) is August (71.6°F).
The months with the lowest average high temperature are January and February (39°F).
- Average low temperature in September: 63.3°F
The month with the highest average low temperature is August (68.2°F).
The coldest month (with the lowest average low temperature) is January (31.6°F).
Average pressure in September
Chatham, MA
- Average pressure in September: 30.05"Hg
The month with the highest atmospheric pressure is November (30.06"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).
Average wind speed in September
Chatham, MA
- Average wind speed in September: 13.5mph
The windiest month (with the highest average wind speed) is January (18mph).
The calmest month (with the lowest average wind speed) is August (11.4mph).
Average humidity in September
Chatham, MA
- Average humidity in September: 80%
The months with the highest relative humidity are June and July (85%).
The month with the lowest relative humidity is November (74%).
Average rainfall in September
Chatham, MA
- Average rainfall in September: 1.85"
The wettest month (with the highest rainfall) is October (2.83").
The driest month (with the least rainfall) is November (1.46").
Average rainfall days in September
Chatham, MA
- Average rainfall days in September: 10.7 days
The month with the highest number of rainy days is May (14.6 days).
The month with the least rainy days is February (8.3 days).
Average snowfall in September
Chatham, MA
- Average snowfall in September: 0"
The month with the highest snowfall is February (1.38").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Chatham, MA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (6 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).
Average sea temperature in September
Chatham, MA
- Average sea temperature in September: 63.8°F
The best month for swimming (with the highest average sea temperature) is August (67.6°F).
The coldest month (with the lowest average sea temperature) is March (39.8°F).
Average daylight in September /
Average sunshine in September
Chatham, MA
- Average daylight in September: 12h and 3min
The month with the longest days is June (Average daylight: 15h and 12min).
The month with the shortest days is December (Average daylight: 9h and 12min).
- Average sunshine in September: 8h and 3min
The month with the most sunshine is August (Average sunshine: 10h and 42min).
The month with the least sunshine is December (Average sunshine: 4h and 18min).
Average sunshine days in September
Chatham, MA
- Average sunshine days in September: 16.9 days
The month with the most sunshine days is August (17.6 days).
The month with the least sunshine days is January (13 days).
Average UV index in September
Chatham, MA
- Average UV index in September: 4
The months with the highest UV index are 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
Chatham, MA
- Average cloud cover in September: 32
The month with the most cloud cover is December (Cloud cover 54).
The month with the least cloud cover is August (Cloud cover 27).
Average visibility in September
Chatham, MA
- 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).
Chatham, Massachusetts, USA
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