September weather forecastHyannis, MA
September
Weather in September
The advent of September in Hyannis indicates a shift from summer to early autumn weather. A modest dip in temperatures on both land and sea signals the change of seasons. However, the sea remains warm enough for various water activities. An absence of snowfall and a moderate UV index make September a favorable time to participate in outdoor activities. Despite shorter daylight hours, the cloud percentage remains stable, offering a consistent weather pattern.Temperature
The advent of September signifies a minor shift to an average high-temperature of a comfortable 67.3°F (19.6°C), aligning closely with August. An average low-temperature of 62.8°F (17.1°C) characterizes Hyannis's September nights.Humidity
In September, the average relative humidity is 79%.Rainfall
In Hyannis, during September, the rain falls for 11.3 days and regularly aggregates up to 1.93" (49mm) of precipitation. In Hyannis, during the entire year, the rain falls for 157.2 days and collects up to 31.77" (807mm) of precipitation.Snowfall
May through November are months without snowfall.Ocean temperature
In Hyannis, Massachusetts, in September, the average water temperature is 64.2°F (17.9°C).Note: Most people find swimming in 64.2°F (17.9°C) to be not enjoyable. The control of one's breathing becomes more challenging as the water temperature drops below 69.8°F (21°C).
Daylight
In Hyannis, the average length of the day in September is 12h and 28min.On the first day of September, sunrise is at 6:07 am and sunset at 7:13 pm. On the last day of the month, sunrise is at 6:37 am and sunset at 6:24 pm EDT.
Sunshine
In Hyannis, Massachusetts, the average sunshine in September is 8.8h.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 unsafe exposure to UV radiation for ordinary individuals.Note: A daily high UV index of 4 in September leads to these guidelines:
Take necessary precautions - Defending against sun damage is advocated. Around midday, solar radiation is most harmful; hence, exposure should be limited. For minimizing sun-related eye damage, always choose sunglasses with UVA and UVB coverage.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Hyannis, MA
- Average high temperature in September: 67.3°F
The warmest month (with the highest average high temperature) is August (72.5°F).
The month with the lowest average high temperature is January (38.3°F).
- Average low temperature in September: 62.8°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 (30.4°F).
Average pressure in September
Hyannis, 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
Hyannis, MA
- Average wind speed in September: 12.6mph
The windiest month (with the highest average wind speed) is January (16.5mph).
The calmest month (with the lowest average wind speed) is August (10.6mph).
Average humidity in September
Hyannis, MA
- Average humidity in September: 79%
The month with the highest relative humidity is July (84%).
The month with the lowest relative humidity is November (74%).
Average rainfall in September
Hyannis, MA
- Average rainfall in September: 1.93"
The wettest month (with the highest rainfall) is October (3.7").
The driest month (with the least rainfall) is August (1.73").
Average rainfall days in September
Hyannis, MA
- Average rainfall days in September: 11.3 days
The month with the highest number of rainy days is April (15.8 days).
The month with the least rainy days is February (10.3 days).
Average snowfall in September
Hyannis, MA
- Average snowfall in September: 0"
The month with the highest snowfall is March (1.93").
The months with the least snowfall are May, June, July, August, September, October and November (0").
Average snowfall days in September
Hyannis, MA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (7.1 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).
Average sea temperature in September
Hyannis, 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
Hyannis, MA
- Average daylight in September: 12h and 30min
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 48min
The month with the most sunshine is August (Average sunshine: 10h and 48min).
The month with the least sunshine is December (Average sunshine: 4h and 36min).
Average sunshine days in September
Hyannis, MA
- Average sunshine days in September: 17.2 days
The month with the most sunshine days is August (17.7 days).
The month with the least sunshine days is February (11.4 days).
Average UV index in September
Hyannis, 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
Hyannis, MA
- Average cloud cover in September: 31
The months with the most cloud cover are February and December (Cloud cover 50).
The month with the least cloud cover is August (Cloud cover 27).
Average visibility in September
Hyannis, 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).
