September weather forecastWellfleet, MA
September
Weather in September
September introduces the early autumn season to Wellfleet, marking a departure from the summer heat. Cooler nights return along with an increase in rain incidents, signifying the start of the transition phase. However, enjoyable late summer weather persists with sea temperatures still at a pleasant 64.3°F (17.9°C), allowing water activities to continue. September combines pleasantly warm days with clear skies, offering spectacular sunset vistas. As September concludes, the full autumn experience unfolds in October.Temperature
The advent of September sees the average high-temperature at a refreshing 66.4°F (19.1°C), subtly shifted from August's 71.1°F (21.7°C). Wellfleet consistently logs a low temperature averaging 62.4°F (16.9°C) during September, a modest drop from daytime temperatures.Humidity
In Wellfleet, the average relative humidity in September is 80%.Rainfall
In September, the rain falls for 10 days. Throughout September, 1.42" (36mm) of precipitation is accumulated. Throughout the year, there are 136.1 rainfall days, and 17.24" (438mm) of precipitation is accumulated.Snowfall
May through October are months without snowfall.Ocean temperature
In September, the average ocean temperature is 64.2°F (17.9°C).Note: Swimming in 64.2°F (17.9°C) does not offer a pleasant experience for most individuals. The act of controlling one's breathing becomes progressively difficult as the water temperature goes under 69.8°F (21°C).
Daylight
In Wellfleet, the average length of the day in September is 12h and 28min.On the first day of September, sunrise is at 6:06 am and sunset at 7:13 pm. On the last day of the month, sunrise is at 6:36 am and sunset at 6:23 pm EDT.
Sunshine
The average sunshine in September is 8.6h.UV index
The average daily maximum UV index in September is 4. A UV Index of 3 to 5 symbolizes a moderate health risk from exposure to the Sun's UV radiation for average individuals.Note: In September, a daily UV index of 4 turns into the following recommendations:
Exercise prevention - Precautions against solar damage are endorsed. To avoid the Sun's strongest rays, limit exposure around the mid-day period. To mitigate harm from sun exposure, pick sunglasses offering UVA and UVB defense.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Wellfleet, MA
- Average high temperature in September: 66.4°F
The warmest month (with the highest average high temperature) is August (71.1°F).
The month with the lowest average high temperature is January (38.7°F).
- Average low temperature in September: 62.4°F
The month with the highest average low temperature is August (67.6°F).
The coldest months (with the lowest average low temperature) are January and February (31.6°F).
Average pressure in September
Wellfleet, 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
Wellfleet, MA
- Average wind speed in September: 13.5mph
The windiest month (with the highest average wind speed) is January (18.5mph).
The calmest months (with the lowest average wind speed) are July and August (11.6mph).
Average humidity in September
Wellfleet, MA
- Average humidity in September: 80%
The month with the highest relative humidity is July (85%).
The month with the lowest relative humidity is November (74%).
Average rainfall in September
Wellfleet, MA
- Average rainfall in September: 1.42"
The wettest month (with the highest rainfall) is October (2.17").
The driest months (with the least rainfall) are February and November (1.18").
Average rainfall days in September
Wellfleet, MA
- Average rainfall days in September: 10 days
The month with the highest number of rainy days is May (14.3 days).
The month with the least rainy days is February (7.3 days).
Average snowfall in September
Wellfleet, MA
- Average snowfall in September: 0"
The month with the highest snowfall is February (0.94").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Wellfleet, MA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (6.1 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).
Average sea temperature in September
Wellfleet, MA
- Average sea temperature in September: 64.3°F
The best month for swimming (with the highest average sea temperature) is August (67.5°F).
The coldest month (with the lowest average sea temperature) is March (39°F).
Average daylight in September /
Average sunshine in September
Wellfleet, MA
- Average daylight in September: 12h and 30min
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 36min
The month with the most sunshine is August (Average sunshine: 10h and 36min).
The month with the least sunshine is December (Average sunshine: 4h and 12min).
Average sunshine days in September
Wellfleet, MA
- Average sunshine days in September: 18.1 days
The month with the most sunshine days is August (18.2 days).
The month with the least sunshine days is December (13.1 days).
Average UV index in September
Wellfleet, 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
Wellfleet, MA
- Average cloud cover in September: 32
The month with the most cloud cover is December (Cloud cover 55).
The month with the least cloud cover is August (Cloud cover 28).
Average visibility in September
Wellfleet, 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).
