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
September indicates a minor shift in the average high-temperature, from August's moderately hot 75.2°F (24°C) to an agreeable 68.9°F (20.5°C). Onset records a slight downturn to an average an enjoyable 61.2°F (16.2°C) during the nights of September.Humidity
In September, the average relative humidity is 79%.Rainfall
September is the month with the least rainfall. Rain falls for 12.3 days and accumulates 1.81" (46mm) of precipitation.Snowfall
In Onset, snow does not fall in May through September.Ocean temperature
In Onset, in September, the average water temperature is 65.8°F (18.8°C).Note: Most people do not enjoy swimming in water that is 65.8°F (18.8°C). Breathing becomes increasingly challenging as the water temperature dips under 69.8°F (21°C).
Daylight
In Onset, the average length of the day in September is 12h and 28min.On the first day of the month, sunrise is at 6:09 am and sunset at 7:15 pm. On the last day of September, sunrise is at 6:39 am and sunset at 6:25 pm EDT.
Sunshine
In September, the average sunshine is 8.7h.UV index
In Onset, the average daily maximum UV index in September is 4. A UV Index of 3 to 5 symbolizes a moderate health risk from unsafe exposure to UV radiation for average individuals.Note: The maximum daily UV index of 4 in September interprets into the following recommendations:
Take precautions - Protection against sunburn is recommended. Exposing oneself to the midday Sun can be harmful due to the strong UV radiation; limit your time outside. A hat with a generous brim can prevent nearly 50% of UV rays from reaching your eyes.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the usual temperature for Onset in September?
What is the average humidity in September?
What is the driest month?
How much does it rain in September?
When it does not snow?
Does it snow in September?
How cold is the water 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 Onset have in September?
How high is the UV index in September?
Average temperature in September
Onset, MA
- Average high temperature in September: 68.9°F
The warmest month (with the highest average high temperature) is July (75.6°F).
The month with the lowest average high temperature is January (36.9°F).
- Average low temperature in September: 61.2°F
The month with the highest average low temperature is August (66.7°F).
The coldest month (with the lowest average low temperature) is January (27.7°F).
Average pressure in September
Onset, 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
Onset, MA
- Average wind speed in September: 10.3mph
The windiest month (with the highest average wind speed) is January (13.7mph).
The calmest month (with the lowest average wind speed) is August (8.7mph).
Average humidity in September
Onset, MA
- Average humidity in September: 79%
The months with the highest relative humidity are June and July (81%).
The months with the lowest relative humidity are March and November (74%).
Average rainfall in September
Onset, MA
- Average rainfall in September: 1.81"
The wettest month (with the highest rainfall) is December (3.58").
The driest month (with the least rainfall) is September (1.81").
Average rainfall days in September
Onset, MA
- Average rainfall days in September: 12.3 days
The month with the highest number of rainy days is July (16 days).
The month with the least rainy days is January (9 days).
Average snowfall in September
Onset, MA
- Average snowfall in September: 0"
The months with the highest snowfall are February and March (2.28").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Onset, 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 and September (0 days).
Average sea temperature in September
Onset, MA
- Average sea temperature in September: 65.8°F
The best month for swimming (with the highest average sea temperature) is August (68.4°F).
The coldest month (with the lowest average sea temperature) is February (38.2°F).
Average daylight in September /
Average sunshine in September
Onset, 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 4min
The month with the most sunshine is August (Average sunshine: 10h and 42min).
The months with the least sunshine are February and December (Average sunshine: 4h and 48min).
Average sunshine days in September
Onset, MA
- Average sunshine days in September: 15.4 days
The month with the most sunshine days is November (16.3 days).
The month with the least sunshine days is April (12.5 days).
Average UV index in September
Onset, 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
Onset, MA
- Average cloud cover in September: 32
The month with the most cloud cover is March (Cloud cover 49).
The month with the least cloud cover is August (Cloud cover 28).
Average visibility in September
Onset, 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).
Onset, Massachusetts, USA
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