September weather forecast
Alton Bay, NH

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Weather in September

September, the first month of the autumn in Alton Bay, is still a pleasant month, with an average temperature fluctuating between 49.6°F (9.8°C) and 69.6°F (20.9°C).

Temperature

September's onset corresponds with a subtle shift in the average high-temperature, slightly moving from a moderately hot 77.2°F (25.1°C) in August to an agreeable 69.6°F (20.9°C). Alton Bay observes an average nighttime temperature of 49.6°F (9.8°C) during September.

Humidity

In September, the average relative humidity is 80%.

Rainfall

September is the month with the least rainfall. Rain falls for 10.8 days and accumulates 1.61" (41mm) of precipitation.

Snowfall

June through September are months without snowfall in Alton Bay.

Daylight

The average length of the day in September is 12h and 29min.
On the first day of the month, sunrise is at 6:09 am and sunset at 7:19 pm. On the last day of September, sunrise is at 6:42 am and sunset at 6:27 pm EDT.

Sunshine

In Alton Bay, the average sunshine in September is 8.2h.

UV index

The average daily maximum UV index in September in Alton Bay is 3. A UV Index reading of 3 to 5 represents a moderate threat to health from unsafe exposure to UV radiation for average individuals.
Note: In September, a daily maximum UV index of 3 leads to the following instructions:
Take care. Persons with lighter skin might suffer burns in less than 30 minutes. Midday is when the Sun's radiation is strongest; avoid prolonged exposure during this time. A wide-brimmed hat is a staple for defending the face, eyes, ears, and neck from the Sun.
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Frequently asked questions

What is the usual temperature for Alton Bay in September?

The high-temperature, in September, in Alton Bay, is 69.6°F (20.9°C), while the low-temperature averages to 49.6°F (9.8°C).

What is the average humidity in September in Alton Bay?

The average relative humidity in September is 80%.

What is the driest month in Alton Bay?

The month with the least rainfall is September, when the rain falls for 10.8 days and typically collects 1.61" (41mm) of precipitation.

How much does it rain in Alton Bay in September?

In Alton Bay, in September, it is raining for 10.8 days, with typically 1.61" (41mm) of accumulated precipitation.

When it does not snow in Alton Bay?

June through September are months without snowfall in Alton Bay, New Hampshire.

Does it snow in Alton Bay in September?

In Alton Bay, New Hampshire, in September, it doesn't snow. In October, it regularly snows.

What is the average length of the day in September in Alton Bay?

The average day length in September in Alton Bay, New Hampshire, is 12h and 29min.

When is the sunrise / sunset in September in Alton Bay?

In September, on the first day of the month, sunrise is at 6:09 am and sunset at 7:19 pm. On the last day of the month, in Alton Bay, sunrise is at 6:42 am and sunset at 6:27 pm EDT.

How long on average sun shines in September in Alton Bay?

In September, the average sunshine duration is 8.2h.

What is the UV index intensity in September in Alton Bay?

In September, the average daily maximum UV index is 3. A UV Index estimate of 3 to 5 represents a medium hazard to health from unprotected exposure to 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
Alton Bay, NH

Average temperature in September - Alton Bay, NH
  • Average high temperature in September: 69.6°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 (26.1°F).

  • Average low temperature in September: 49.6°F

The month with the highest average low temperature is July (57.6°F).
The coldest month (with the lowest average low temperature) is January (12.9°F).

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Average pressure in September
Alton Bay, NH

Average pressure in September - Alton Bay, 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).

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Average wind speed in September
Alton Bay, NH

Average wind speed in September - Alton Bay, NH
  • Average wind speed in September: 4.8mph

The windiest months (with the highest average wind speed) are January and February (7.1mph).
The calmest months (with the lowest average wind speed) are July and August (4.7mph).

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Average humidity in September
Alton Bay, NH

Average humidity in September - Alton Bay, NH
  • Average humidity in September: 80%

The months with the highest relative humidity are January and February (86%).
The month with the lowest relative humidity is April (76%).

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Average rainfall in September
Alton Bay, NH

Average rainfall in September - Alton Bay, NH
  • Average rainfall in September: 1.61"

The wettest month (with the highest rainfall) is October (3.19").
The driest month (with the least rainfall) is September (1.61").

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Average rainfall days in September
Alton Bay, NH

Average rainfall days in September - Alton Bay, NH
  • Average rainfall days in September: 10.8 days

The month with the highest number of rainy days is April (15.8 days).
The month with the least rainy days is February (8.3 days).

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Average snowfall in September
Alton Bay, NH

Average snowfall in September - Alton Bay, NH
  • Average snowfall in September: 0"

The month with the highest snowfall is February (9.84").
The months with the least snowfall are June, July, August and September (0").

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Average snowfall days in September
Alton Bay, NH

Average snowfall days in September - Alton Bay, NH
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is January (13.2 days).
The months with the least snowfall days are June, July, August and September (0 days).

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Average daylight in September /
Average sunshine in September
Alton Bay, NH

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

The month with the longest days is June (Average daylight: 15h and 24min).
The month with the shortest days is December (Average daylight: 9h and 0min).

  • Average sunshine in September: 8h and 1min

The month with the most sunshine is August (Average sunshine: 10h and 12min).
The month with the least sunshine is February (Average sunshine: 4h and 30min).

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Average sunshine days in September
Alton Bay, NH

Average sunshine days in September - Alton Bay, NH
  • Average sunshine days in September: 16.9 days

The month with the most sunshine days is September (16.9 days).
The month with the least sunshine days is April (11.4 days).

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Average UV index in September
Alton Bay, NH

Average UV index in September - Alton Bay, NH
  • Average UV index in September: 3

The months with the highest UV index are June, July and August (UV index 5).
The months with the lowest UV index are January, February, March, October, November and December (UV index 2).

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Average cloud cover in September
Alton Bay, NH

Average cloud cover in September - Alton Bay, NH
  • Average cloud cover in September: 39

The month with the most cloud cover is March (Cloud cover 52).
The month with the least cloud cover is August (Cloud cover 35).

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Average visibility in September
Alton Bay, NH

Average visibility in September - Alton Bay, NH
  • Average visibility in September: 4mi

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

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Alton Bay, New Hampshire, USA

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