September weather forecast
Mount Washington, NH

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Weather in September

September marks the transition from summer to autumn in Mount Washington. September enjoys warm temperatures despite shorter daylight hours, making it a lovely time to embrace the outdoors. The highest recorded temperature in September drops to 66°F (18.9°C), and it offers minim rainfall of 0.94" (24mm). The weather in September is perfect for visitors wanting to witness the onset of fall foliage, with the landscape gradually turning into beautiful hues of orange and brown.

Temperature

As September arrives, Mount Washington's weather displays a minor decrease in high-temperatures, transitioning from August's pleasant 73°F (22.8°C) to a refreshing 66°F (18.9°C). Mount Washington, in the month of September, anticipates a consistent average low-temperature of 46.9°F (8.3°C).

Humidity

In Mount Washington, the average relative humidity in September is 80%.

Rainfall

September is the month with the least rainfall. Rain falls for 10.6 days and accumulates 0.94" (24mm) of precipitation.

Snowfall

June through September are months without snowfall.

Daylight

The average length of the day in September is 12h and 30min.
On the first day of September in Mount Washington, sunrise is at 6:09 am and sunset at 7:20 pm. On the last day of the month, sunrise is at 6:42 am and sunset at 6:27 pm EDT.

Sunshine

In September, the average sunshine is 8.3h.

UV index

In Mount Washington, the average daily maximum UV index in September is 3. A UV Index of 3 to 5 symbolizes a medium vulnerability from exposure to the Sun's UV radiation for the ordinary person.
Note: The maximum daily UV index, 3 in September, converts into the following recommendations:
Make use of precautions - Shielding skin and eyes from injury is a requirement. Direct exposure to the Sun's intense radiation around midday should be avoided for health reasons. For a sun-safe wardrobe, go for clothes that are tightly woven and generously sized.
Updated: Jul 30, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What are the temperatures in September?

In September, in Mount Washington, the average high-temperature is 66°F (18.9°C), and the average low-temperature is 46.9°F (8.3°C).

What is the average humidity in September?

In September, the average relative humidity is 80%.

What is the driest month?

September is the month with the least rainfall. Rain falls for 10.6 days and accumulates 0.94" (24mm) of precipitation.

How many days does it rain in September?

In September, the rain falls for 10.6 days. Throughout September, 0.94" (24mm) of precipitation is accumulated.

When it does not snow?

June through September are months without snowfall.

Does it snow in September?

In Mount Washington, in September, it doesn't snow. In October, it regularly snows.

What is the average length of the day in September?

In September, the average day length in Mount Washington is 12h and 30min.

What time are sunrise and sunset in September?

In September, on the first day of the month, sunrise is at 6:09 am and sunset at 7:20 pm. On the last day of the month, sunrise is at 6:42 am and sunset at 6:27 pm EDT.

How long on average sun shines in September?

In Mount Washington, the average sunshine duration in September is 8.3h.

What is the UV index reading in September?

The average daily maximum UV index in September is 3. A UV Index of 3 to 5 symbolizes a medium health risk from exposure to the Sun's UV radiation.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Mount Washington, NH

Average temperature in September - Mount Washington, NH
  • Average high temperature in September: 66°F

The warmest month (with the highest average high temperature) is July (75°F).
The month with the lowest average high temperature is January (21.7°F).

  • Average low temperature in September: 46.9°F

The month with the highest average low temperature is July (54.7°F).
The coldest month (with the lowest average low temperature) is January (8.4°F).

Average pressure in September
Mount Washington, NH

Average pressure in September - Mount Washington, 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 (29.91"Hg).

Average wind speed in September
Mount Washington, NH

Average wind speed in September - Mount Washington, NH
  • Average wind speed in September: 4.6mph

The windiest month (with the highest average wind speed) is February (9.8mph).
The calmest month (with the lowest average wind speed) is August (4.4mph).

Average humidity in September
Mount Washington, NH

Average humidity in September - Mount Washington, NH
  • Average humidity in September: 80%

The month with the highest relative humidity is February (90%).
The month with the lowest relative humidity is May (77%).

Average rainfall in September
Mount Washington, NH

Average rainfall in September - Mount Washington, NH
  • Average rainfall in September: 0.94"

The wettest month (with the highest rainfall) is April (2.44").
The driest month (with the least rainfall) is September (0.94").

Average rainfall days in September
Mount Washington, NH

Average rainfall days in September - Mount Washington, NH
  • Average rainfall days in September: 10.6 days

The month with the highest number of rainy days is July (16.7 days).
The month with the least rainy days is November (8 days).

Average snowfall in September
Mount Washington, NH

Average snowfall in September - Mount Washington, NH
  • Average snowfall in September: 0"

The month with the highest snowfall is January (11.42").
The months with the least snowfall are June, July, August and September (0").

Average snowfall days in September
Mount Washington, NH

Average snowfall days in September - Mount Washington, NH
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is January (20.4 days).
The months with the least snowfall days are July, August and September (0 days).

Average daylight in September /
Average sunshine in September
Mount Washington, NH

Average daylight in September / Average sunshine in September - Mount Washington, NH
  • Average daylight in September: 12h and 3min

The month with the longest days is June (Average daylight: 15h and 30min).
The month with the shortest days is December (Average daylight: 8h and 54min).

  • Average sunshine in September: 8h and 2min

The month with the most sunshine is August (Average sunshine: 9h and 48min).
The month with the least sunshine is February (Average sunshine: 3h and 30min).

Average sunshine days in September
Mount Washington, NH

Average sunshine days in September - Mount Washington, NH
  • Average sunshine days in September: 16.2 days

The month with the most sunshine days is September (16.2 days).
The month with the least sunshine days is February (7.8 days).

Average UV index in September
Mount Washington, NH

Average UV index in September - Mount Washington, NH
  • Average UV index in September: 3

The months with the highest UV index are June and July (UV index 5).
The months with the lowest UV index are February and December (UV index 1).

Average cloud cover in September
Mount Washington, NH

Average cloud cover in September - Mount Washington, NH
  • Average cloud cover in September: 41

The month with the most cloud cover is February (Cloud cover 64).
The months with the least cloud cover are July, August and September (Cloud cover 41).

Average visibility in September
Mount Washington, NH

Average visibility in September - Mount Washington, NH
  • Average visibility in September: 4mi

The months with the highest visibility are May, June and July (5mi).
The months with the lowest visibility are January, February, March, April, August, September, October, November and December (4mi).

Mount Washington, New Hampshire, USA

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