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
The arrival of September correlates with a minor temperature reduction, down from August's warm 75.7°F (24.3°C) to a pleasant 69.1°F (20.6°C). During the month of September, the temperature generally drops to a low average of 56.1°F (13.4°C).Humidity
In September, the average relative humidity is 79%.Rainfall
September is the month with the least rainfall. Rain falls for 11.3 days and accumulates 1.54" (39mm) of precipitation.Snowfall
In Portsmouth, snow does not fall in May through September.Ocean temperature
In Portsmouth, in September, the average water temperature is 61.9°F (16.6°C).Note: For the majority, swimming in 61.9°F (16.6°C) does not offer a pleasant experience. Below 69.8°F (21°C), the difficulty in controlling breathing escalates.
Daylight
In September, the average length of the day is 12h and 29min.On the first day of September in Portsmouth, New Hampshire, sunrise is at 6:08 am and sunset at 7:17 pm. On the last day of the month, sunrise is at 6:40 am and sunset at 6:25 pm EDT.
Sunshine
In September, the average sunshine in Portsmouth is 8.6h.UV index
In Portsmouth, the average daily maximum UV index in September is 4. A UV Index value of 3 to 5 symbolizes a moderate health risk from unsafe exposure to UV radiation for average individuals.Note: A maximum daily UV index of 4 during September morphs into the following directions:
Take precautions - Protection against sunburn is recommended. Direct exposure to the Sun during its peak hours around mid-day should be minimized for safety. Using UVA and UVB-protective sunglasses and sun-protective clothing is effective against UV radiation.
Frequently asked questions
What is the average September temperature in Portsmouth?
What is the average humidity in September in Portsmouth?
What is the driest month in Portsmouth?
How much does it rain in Portsmouth in September?
When it does not snow in Portsmouth?
Does it snow in Portsmouth in September?
What is the ocean temperature in September in Portsmouth?
What is the average length of the day in September in Portsmouth?
What time are sunrise and sunset in September in Portsmouth?
How long on average sun shines in September in Portsmouth?
What is the UV index intensity in September in Portsmouth?
Average temperature in September
Portsmouth, NH
- Average high temperature in September: 69.1°F
The warmest month (with the highest average high temperature) is July (76.3°F).
The month with the lowest average high temperature is January (31.8°F).
- Average low temperature in September: 56.1°F
The month with the highest average low temperature is July (62.6°F).
The coldest month (with the lowest average low temperature) is January (21.2°F).
Average pressure in September
Portsmouth, NH
- 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 (29.92"Hg).
Average wind speed in September
Portsmouth, NH
- Average wind speed in September: 7.6mph
The windiest month (with the highest average wind speed) is January (11.7mph).
The calmest month (with the lowest average wind speed) is July (6.6mph).
Average humidity in September
Portsmouth, NH
- Average humidity in September: 79%
The month with the highest relative humidity is June (80%).
The months with the lowest relative humidity are April and November (75%).
Average rainfall in September
Portsmouth, NH
- Average rainfall in September: 1.54"
The wettest month (with the highest rainfall) is October (2.83").
The driest month (with the least rainfall) is September (1.54").
Average rainfall days in September
Portsmouth, NH
- Average rainfall days in September: 11.3 days
The month with the highest number of rainy days is June (15 days).
The month with the least rainy days is January (7.5 days).
Average snowfall in September
Portsmouth, NH
- Average snowfall in September: 0"
The month with the highest snowfall is January (4.02").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Portsmouth, NH
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (8.8 days).
The months with the least snowfall days are May, June, July, August and September (0 days).
Average sea temperature in September
Portsmouth, NH
- Average sea temperature in September: 61.9°F
The best month for swimming (with the highest average sea temperature) is August (65.6°F).
The coldest month (with the lowest average sea temperature) is March (38.5°F).
Average daylight in September /
Average sunshine in September
Portsmouth, NH
- Average daylight in September: 12h and 3min
The month with the longest days is June (Average daylight: 15h and 18min).
The month with the shortest days is December (Average daylight: 9h and 6min).
- Average sunshine in September: 8h and 4min
The month with the most sunshine is August (Average sunshine: 10h and 36min).
The months with the least sunshine are February and December (Average sunshine: 4h and 48min).
Average sunshine days in September
Portsmouth, NH
- Average sunshine days in September: 16.8 days
The month with the most sunshine days is September (16.8 days).
The month with the least sunshine days is April (13.2 days).
Average UV index in September
Portsmouth, NH
- 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
Portsmouth, NH
- Average cloud cover in September: 33
The month with the most cloud cover is March (Cloud cover 50).
The month with the least cloud cover is August (Cloud cover 29).
Average visibility in September
Portsmouth, NH
- 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, New Hampshire, USA
Weather forecast for your location
2. Allow the app to use your location
