September weather forecast and climate
Granby, CO

Weather in September

September, the first month of the autumn, in Granby, is still a comfortable month, with average temperature fluctuating between 64.4°F (18°C) and 36.9°F (2.7°C).

Temperature

In Granby, the average high-temperature marginally drops, from an agreeable 71.2°F (21.8°C) in August, to a comfortable 64.4°F (18°C). The average low-temperature, in September, is 36.9°F (2.7°C).

Humidity

The average relative humidity in September is 52%.

Rainfall

In Granby, in September, during 7.1 rainfall days, 0.59" (15mm) of precipitation is typically accumulated. Throughout the year, there are 96.3 rainfall days, and 11.54" (293mm) of precipitation is accumulated.

Snowfall

January through June, August through December are months with snowfall. In Granby, Colorado, during September, snow falls for 2 days and regularly aggregates up to 0.87" (22mm) of snow. In Granby, during the entire year, snow falls for 110.7 days, and aggregates up to 59.88" (1521mm) of snow.

Daylight

In September, the average length of the day is 12.4h.

Sunshine

In September, the average sunshine is 11.2h.

UV index

The average daily maximum UV index in Granby is 3. A UV Index of 3 to 5 symbolizes a medium health hazard from the exposure to the Sun's UV radiation for average individuals.
Note: The daily maximum UV index of 3 interpret into the following advice:
Take precautions - Protection against sunburn is recommended. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects. Caution! The reflection of snow can nearly double the intensity of the Sun's UV radiation.
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FAQ

What is the temperature in September in Granby?

In Granby, in September, the average high-temperature is 64.4°F (18°C), and the average low-temperature is 36.9°F (2.7°C).

What is the average humidity in September in Granby?

The average relative humidity in September in Granby, Colorado, is 52%.

How much does it rain in Granby in September?

In Granby, in September, during 7.1 rainfall days, 0.59" (15mm) of precipitation is typically accumulated.

How much does it snow in Granby in September?

In Granby, in September, during 2 snowfall days, 0.87" (22mm) of snow is typically accumulated.

How many hours of daylight does Granby have in September?

The average length of the day in September is 12.4h.

How many hours of sunshine does Granby have in September?

In September, the average sunshine in Granby, Colorado, is 11.2h.

How high is the UV index in September in Granby?

The average daily maximum UV index in September is 3. A UV Index value of 3 to 5 symbolizes a moderate health threat from unsafe exposure to the Sun's UV rays.

Average temperature in September
Granby, CO

Average temperature in September - Granby, CO
  • Average high temperature in September: 64.4°F

The warmest month (with the highest average high temperature) is July (72.3°F).
The month with the lowest average high temperature is December (24.6°F).

  • Average low temperature in September: 36.9°F

The month with the highest average low temperature is July (43.7°F).
The coldest month (with the lowest average low temperature) is January (4.3°F).

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Average pressure in September
Granby, CO

Average pressure in September - Granby, CO
  • Average pressure in September: 30.03"

The month with the highest atmospheric pressure is January (30.19").
Months with the lowest atmospheric pressure are April, May and June (29.93").

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Average wind speed in September
Granby, CO

Average wind speed in September - Granby, CO
  • Average wind speed in September: 5.5mph

The windiest month (with the highest average wind speed) is February (7mph).
The calmest month (with the lowest average wind speed) is August (5mph).

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Average humidity in September
Granby, CO

Average humidity in September - Granby, CO
  • Average humidity in September: 52%

The month with the highest relative humidity is February (87%).
The month with the lowest relative humidity is June (49%).

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Average rainfall in September
Granby, CO

Average rainfall in September - Granby, CO
  • Average rainfall in September: 0.59"

The wettest month (with the highest rainfall) is May (1.73").
The driest month (with the least rainfall) is August (0.55").

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Average rainfall days in September
Granby, CO

Average rainfall days in September - Granby, CO
  • Average rainfall days in September: 7.1 days

The month with the highest number of rainy days is May (12.8 days).
The month with the least rainy days is October (4.9 days).

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Average snowfall in September
Granby, CO

Average snowfall in September - Granby, CO
  • Average snowfall in September: 0.87"

The month with the highest snowfall is April (10.94").
The month with the least snowfall is July (0").

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Average snowfall days in September
Granby, CO

Average snowfall days in September - Granby, CO
  • Average snowfall days in September: 2 days

The month with the highest number of snowfall days is February (16.1 days).
The month with the least snowfall days is July (0 days).

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Average daylight in September /
Average sunshine in September
Granby, CO

Average daylight in September / Average sunshine in September - Granby, CO
  • Average daylight in September: 12.4h

The month with the longest days is June (Average daylight: 15h).
The month with the shortest days is December (Average daylight: 9.4h).

  • Average sunshine in September: 11.2h

Months with the most sunshine are July and August (Average sunshine: 11.8h).
The month with the least sunshine is February (Average sunshine: 6.2h).

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Average sunshine days in September
Granby, CO

Average sunshine days in September - Granby, CO
  • Average sunshine days in September: 19.5 days

Months with the most sunshine days are September and November (19.5 days).
The month with the least sunshine days is May (9.5 days).

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Average UV index in September
Granby, CO

Average UV index in September - Granby, CO
  • Average UV index in September: 3

Months with the highest UV index are June, July and August (UV index 4).
Months with the lowest UV index are January, February, March, April, October, November and December (UV index 2).

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Average cloud cover in September
Granby, CO

Average cloud cover in September - Granby, CO
  • Average cloud cover in September: 15

The month with the most cloud cover is February (Cloud cover 41).
The month with the least cloud cover is September (Cloud cover 15).

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Average visibility in September
Granby, CO

Average visibility in September - Granby, CO
  • Average visibility in September: 6mi

Months with the highest visibility are May, June, July, August, September, October and November (6mi).
Months with the lowest visibility are January, February, March, April and December (5mi).

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