September weather forecast
Chatham, MA

The calm blue water and white sand on a typical beach in Cape Cod, with a visible path and a far view of the high Chatham Lighthouse, Massachusetts
The calm blue water and white sand on a typical beach in Cape Cod, with a visible path and a far view of the high Chatham Lighthouse, Massachusetts

Weather in September

The first month of the autumn, September, is still a comfortable month in Chatham, Massachusetts, with an average temperature varying between 63.3°F (17.4°C) and 66.6°F (19.2°C).

Temperature

In September, the average high-temperature is almost the same as in August - an enjoyable 66.6°F (19.2°C). In Chatham, the average low-temperature is 63.3°F (17.4°C).

Humidity

In Chatham, the average relative humidity in September is 80%.

Rainfall

In Chatham, during 10.7 rainfall days, 1.85" (47mm) of precipitation is typically accumulated. Throughout the year, in Chatham, Massachusetts, there are 142.4 rainfall days, and 22.09" (561mm) of precipitation is accumulated.

Snowfall

May through October are months without snowfall in Chatham.

Ocean temperature

In Chatham, in September, the average water temperature is 63.9°F (17.7°C).
Note: Swimming in 63.9°F (17.7°C) is not enjoyable for the majority. Controlling breathing becomes progressively more difficult as surface water temperature decreases below 69.8°F (21°C).

Daylight

In September, the average length of the day in Chatham is 12h and 28min.
On the first day of September in Chatham, sunrise is at 6:06 am and sunset at 7:13 pm. On the last day of the month, sunrise is at 6:35 am and sunset at 6:23 pm EDT.

Sunshine

The average sunshine in September is 8.5h.

UV index

In Chatham, the average daily maximum UV index in September is 4. A UV Index estimate of 3 to 5 represents a medium health hazard from unprotected exposure to Sun's UV rays for the average person.
Note: The daily maximum UV index of 4 in September interpret into the following advice:
Take precautions - Protection against sunburn is recommended. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects.
[Resources]

FAQ

What is the temperature in September in Chatham?

In September, in Chatham, Massachusetts, the average high-temperature is 66.6°F (19.2°C), and the average low-temperature is 63.3°F (17.4°C).

What is the average humidity in September in Chatham?

The average relative humidity in September in Chatham, Massachusetts, is 80%.

How much does it rain in Chatham in September?

In Chatham, in September, it is raining for 10.7 days, with typically 1.85" (47mm) of accumulated precipitation.

When it does not snow in Chatham?

In Chatham, Massachusetts, snow does not fall in May through October.

What is the ocean temperature in September in Chatham?

In Chatham, the average seawater temperature in September is 63.9°F (17.7°C). For most, swimming in 63.9°F (17.7°C) is not an enjoyable activity. Furthermore, controlling your breathing becomes progressively more difficult as the water temperature decreases from 69.8°F (21°C) to 59°F (15°C).

What is the average length of the day in September in Chatham?

In Chatham, Massachusetts, the average day length in September is 12h and 28min.

When are sunrise and sunset in September in Chatham?

On the first day of September in Chatham, Massachusetts, sunrise is at 6:06 am and sunset at 7:13 pm. On the last day of the month, sunrise is at 6:35 am and sunset at 6:23 pm EDT.

How long on average sun shines in September in Chatham?

The average sunshine duration in September is 8.5h.

What is the UV index reading in September in Chatham?

The average daily maximum UV index in September in Chatham, Massachusetts, is 4. A UV Index estimate of 3 to 5 represents a medium health risk from unprotected exposure to UV radiation.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Chatham, MA

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).

[Resources]

Average pressure in September
Chatham, MA

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).

[Resources]

Average wind speed in September
Chatham, MA

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).

[Resources]

Average humidity in September
Chatham, MA

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%).

[Resources]

Average rainfall in September
Chatham, MA

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").

[Resources]

Average rainfall days in September
Chatham, MA

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).

[Resources]

Average snowfall in September
Chatham, MA

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").

[Resources]

Average snowfall days in September
Chatham, MA

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).

[Resources]

Average sea temperature in September
Chatham, MA

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).

[Resources]

Average daylight in September /
Average sunshine in September
Chatham, MA

Average daylight in September / Average sunshine in September - Chatham, MA
  • Average daylight in September: 12h and 28min

The month with the longest days is June (Average daylight: 15h and 9min).
The month with the shortest days is December (Average daylight: 9h and 13min).

  • Average sunshine in September: 8h and 30min

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).

[Resources]

Average sunshine days in September
Chatham, MA

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).

[Resources]

Average UV index in September
Chatham, MA

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).

[Resources]

Average cloud cover in September
Chatham, MA

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).

[Resources]

Average visibility in September
Chatham, MA

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).

[Resources]

Weather forecast for your location

1. Click Locate me button
2. Allow the app to use your location
* you will be automatically redirected to the weather forecast for your location