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
Onset's September weather features a light decline in high-temperatures, reducing from a warm 75.2°F (24°C) in August to a pleasant 68.9°F (20.5°C). With a barely noticeable fluctuation in temperature, Onset reaches an average low of 61.2°F (16.2°C) during the September nights.Humidity
In Onset, the average relative humidity in September is 79%.Rainfall
The month with the least rainfall in Onset is September, when the rain falls for 12.3 days and typically collects 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: A majority do not enjoy swimming in water at 65.8°F (18.8°C). The difficulty in controlling breathing increases progressively as the temperature dips below 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 Onset, the average sunshine in September is 8.7h.UV index
The average daily maximum UV index in September is 4. A UV Index reading of 3 to 5 represents a moderate threat to health from exposure to the Sun's UV rays for the ordinary person.Note: A daily high UV index of 4 in September leads to these guidelines:
Be vigilant - Preventing sunburn is recommended. Solar radiation peaks around mid-day, so it's wise to limit exposure to the Sun at this time. Wearing a wide-brim hat can block approximately 50% of UV radiation, protecting the eyes.
Frequently asked questions
What are the temperatures in Onset in September?
What is the average humidity in September in Onset?
What is the driest month in Onset?
How much does it rain in Onset in September?
When it does not snow in Onset?
Does it snow in Onset in September?
What is the ocean temperature in September in Onset?
What is the average length of the day in September in Onset?
What time are sunrise and sunset in September in Onset?
How many hours of sunshine does Onset have in September?
What is the UV index reading in September in Onset?
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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