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 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
A mild drop in Portsmouth's average high-temperature is observed in September, transitioning from a moderately hot 77.7°F (25.4°C) in August to an agreeable 71.4°F (21.9°C). Portsmouth's September nights cool down to an average low-temperature of 59.7°F (15.4°C).Humidity
In Portsmouth, the average relative humidity in September is 78%.Rainfall
September is the month with the least rainfall. Rain falls for 11.6 days and accumulates 1.42" (36mm) of precipitation.Snowfall
In Portsmouth, snow does not fall in April, June through October.Daylight
In September, the average length of the day is 12h and 28min.On the first day of September in Portsmouth, sunrise is at 6:11 am and sunset at 7:17 pm. On the last day of the month, sunrise is at 6:41 am and sunset at 6:27 pm EDT.
Sunshine
In Portsmouth, the average sunshine in September is 8.7h.UV index
In Portsmouth, the average daily maximum UV index in September is 4. A UV Index reading of 3 to 5 represents a moderate health risk from unprotected exposure to Sun's UV rays for the average person.Note: In September, a daily maximum UV index of 4 leads to the following instructions:
Exercise prudence. Persons with fair skin could be burned in under 30 minutes. Avoiding the Sun during its peak radiation time around midday is a healthy practice. Stay sun-safe with clothing that is both closely woven and worn loosely.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What are the temperatures in September?
What is the average humidity in September?
What is the driest month?
How many days does it rain in September?
When it does not snow?
What is the average length of the day in September?
When are sunrise and sunset in September?
How many hours of sunshine does Portsmouth have in September?
What is the UV index intensity in September?
Average temperature in September
Portsmouth, RI
- Average high temperature in September: 71.4°F
The warmest month (with the highest average high temperature) is July (78.3°F).
The month with the lowest average high temperature is January (36.1°F).
- Average low temperature in September: 59.7°F
The month with the highest average low temperature is July (66.7°F).
The coldest month (with the lowest average low temperature) is January (26.4°F).
Average pressure in September
Portsmouth, RI
- Average pressure in September: 30.05"Hg
The month with the highest atmospheric pressure is November (30.07"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).
Average wind speed in September
Portsmouth, RI
- Average wind speed in September: 9mph
The windiest month (with the highest average wind speed) is January (12.1mph).
The calmest month (with the lowest average wind speed) is August (8.1mph).
Average humidity in September
Portsmouth, RI
- Average humidity in September: 78%
The month with the highest relative humidity is June (81%).
The month with the lowest relative humidity is March (73%).
Average rainfall in September
Portsmouth, RI
- Average rainfall in September: 1.42"
The wettest month (with the highest rainfall) is October (3.27").
The driest month (with the least rainfall) is September (1.42").
Average rainfall days in September
Portsmouth, RI
- Average rainfall days in September: 11.6 days
The month with the highest number of rainy days is April (15.6 days).
The month with the least rainy days is January (8.3 days).
Average snowfall in September
Portsmouth, RI
- Average snowfall in September: 0"
The month with the highest snowfall is February (2.76").
The months with the least snowfall are April, June, July, August, September and October (0").
Average snowfall days in September
Portsmouth, RI
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (6.6 days).
The months with the least snowfall days are June, July, August, September and October (0 days).
Average daylight in September /
Average sunshine in September
Portsmouth, RI
- Average daylight in September: 12h and 3min
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 4min
The month with the most sunshine is August (Average sunshine: 10h and 30min).
The month with the least sunshine is February (Average sunshine: 4h and 48min).
Average sunshine days in September
Portsmouth, RI
- Average sunshine days in September: 15.8 days
The month with the most sunshine days is November (17.7 days).
The month with the least sunshine days is April (12.3 days).
Average UV index in September
Portsmouth, RI
- Average UV index in September: 4
The months with the highest UV index are June, July and August (UV index 6).
The months with the lowest UV index are January, February, March and December (UV index 2).
Average cloud cover in September
Portsmouth, RI
- Average cloud cover in September: 33
The month with the most cloud cover is March (Cloud cover 48).
The month with the least cloud cover is August (Cloud cover 29).
Average visibility in September
Portsmouth, RI
- 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).
Portsmouth, Rhode Island, USA
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