September weather forecastMerrimack, NH
September
Weather in September
September carries a hint of autumn in the air as Residents of Merrimack slightly feel the diminishing warmth. Despite a increasing humidity, the breeze carries a pleasant nip that adds to the city's climate charm. Subtle changes in the landscape become evident as leaves start turning different hues. As a consolation to receding summer, September boasts an average of 12.5 hours of daylight. Combined with the instinctive cultural change, September's weather creates an appealing mélange of nature and festivities.Temperature
Merrimack in September experiences a gentle temperature dip, with average high-temperatures reducing from a moderately hot 80.1°F (26.7°C) in August to an agreeable 72.1°F (22.3°C). Throughout the month of September, Merrimack observes an average nighttime temperature of 54°F (12.2°C).Humidity
In September, the average relative humidity is 77%.Rainfall
In Merrimack, in September, during 8.4 rainfall days, 0.79" (20mm) of precipitation is typically accumulated. Throughout the year, in Merrimack, New Hampshire, there are 104.4 rainfall days, and 12.95" (329mm) of precipitation is accumulated.Snowfall
In Merrimack, snow does not fall in June through September.Daylight
In September, the average length of the day in Merrimack is 12h and 29min.On the first day of the month, sunrise is at 6:11 am and sunset at 7:20 pm. On the last day of September, sunrise is at 6:42 am and sunset at 6:28 pm EDT.
Sunshine
In September, the average sunshine in Merrimack, New Hampshire, is 8.4h.UV index
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: The daily maximum UV index of 4 in September interprets into the following advice:
Preventative actions are necessary - Suggestions to safeguard against sun damage are in order. Direct Sun exposure should be minimized especially during midday when radiation is most intense. Sun-related eye harm can be minimized with proper sunglasses offering UVA and UVB coverage.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Merrimack, NH
- Average high temperature in September: 72.1°F
The warmest month (with the highest average high temperature) is July (81.7°F).
The month with the lowest average high temperature is January (30.6°F).
- Average low temperature in September: 54°F
The month with the highest average low temperature is July (61°F).
The coldest month (with the lowest average low temperature) is January (18°F).
Average pressure in September
Merrimack, NH
- 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 (29.92"Hg).
Average wind speed in September
Merrimack, NH
- Average wind speed in September: 5.5mph
The windiest month (with the highest average wind speed) is January (8.3mph).
The calmest month (with the lowest average wind speed) is August (5.1mph).
Average humidity in September
Merrimack, NH
- Average humidity in September: 77%
The month with the highest relative humidity is February (81%).
The month with the lowest relative humidity is April (72%).
Average rainfall in September
Merrimack, NH
- Average rainfall in September: 0.79"
The wettest month (with the highest rainfall) is October (1.38").
The driest month (with the least rainfall) is January (0.75").
Average rainfall days in September
Merrimack, NH
- Average rainfall days in September: 8.4 days
The month with the highest number of rainy days is June (12.1 days).
The month with the least rainy days is January (4.1 days).
Average snowfall in September
Merrimack, NH
- Average snowfall in September: 0"
The month with the highest snowfall is December (2.99").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in September
Merrimack, NH
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (7.1 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Merrimack, NH
- Average daylight in September: 12h and 30min
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 24min
The month with the most sunshine is August (Average sunshine: 10h and 24min).
The month with the least sunshine is February (Average sunshine: 4h and 36min).
Average sunshine days in September
Merrimack, NH
- Average sunshine days in September: 20 days
The months with the most sunshine days are January and December (21.3 days).
The month with the least sunshine days is June (16.7 days).
Average UV index in September
Merrimack, NH
- 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, November and December (UV index 2).
Average cloud cover in September
Merrimack, NH
- Average cloud cover in September: 37
The month with the most cloud cover is March (Cloud cover 51).
The month with the least cloud cover is August (Cloud cover 33).
Average visibility in September
Merrimack, NH
- Average visibility in September: 5mi
The months with the highest visibility are January, April, November and December (6mi).
The months with the lowest visibility are February, March, May, June, July, August, September and October (5mi).
