September weather forecast
Silverthorne, CO

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Weather in September

The first month of the autumn, September, is also a moderate month in Silverthorne, Colorado, with an average temperature fluctuating between 33.6°F (0.9°C) and 59.7°F (15.4°C).

Temperature

As September arrives, Silverthorne's weather displays a minor decrease in high-temperatures, transitioning from August's enjoyable 65.8°F (18.8°C) to a moderate 59.7°F (15.4°C). In September, the temperature registers a significant dip to an average of 33.6°F (0.9°C) at night.

Humidity

The average relative humidity in September in Silverthorne, Colorado, is 58%.

Rainfall

September is the month with the least rainfall. Rain falls for 9.8 days and accumulates 0.91" (23mm) of precipitation.

Snowfall

January through December are months with snowfall in Silverthorne. In Silverthorne, Colorado, during September, snow falls for 3.5 days and regularly aggregates up to 0.94" (24mm) of snow. In Silverthorne, during the entire year, snow falls for 139.9 days and aggregates up to 89.53" (2274mm) of snow.

Daylight

The average length of the day in September is 12h and 26min.
On the first day of the month, sunrise is at 6:33 am and sunset at 7:34 pm. On the last day of September, sunrise is at 7:00 am and sunset at 6:47 pm MDT.

Sunshine

In September, the average sunshine is 10.9h.

UV index

In Silverthorne, the average daily maximum UV index in September is 3. A UV Index reading of 3 to 5 represents a moderate health risk from exposure to the Sun's UV rays for the average person.
Note: The daily high UV index of 3 in September translates into this advice:
Be mindful. Individuals with a lighter skin tone may suffer burns in less than 30 minutes. Avoiding the Sun's peak radiation during midday hours is essential for health and safety. Loose clothes with a tight weave are optimal for safeguarding yourself against the Sun's rays. Be aware! The intensity of the Sun's UV radiation can be amplified nearly twice due to snow reflection.
Updated: Feb 10, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What are the temperatures in Silverthorne in September?

Silverthorne in September has an average high-temperature of 59.7°F (15.4°C) and an average low-temperature of 33.6°F (0.9°C).

What is the average humidity in September in Silverthorne?

In September, the average relative humidity is 58%.

What is the driest month in Silverthorne?

September is the month with the least rainfall in Silverthorne, Colorado. Rain falls for 9.8 days and accumulates 0.91" (23mm) of precipitation.

How much does it rain in Silverthorne in September?

In Silverthorne, in September, it is raining for 9.8 days, with typically 0.91" (23mm) of accumulated precipitation.

How much does it snow in Silverthorne in September?

In Silverthorne, during September, snow falls for 3.5 days and regularly aggregates up to 0.94" (24mm) of snow.

How many hours of daylight does Silverthorne have in September?

In September, the average day length is 12h and 26min.

What time are sunrise and sunset in September in Silverthorne?

In September, on the first day of the month, sunrise is at 6:33 am and sunset at 7:34 pm. On the last day of the month, in Silverthorne, Colorado, sunrise is at 7:00 am and sunset at 6:47 pm MDT.

How many hours of sunshine does Silverthorne have in September?

The average sunshine duration in September in Silverthorne is 10.9h.

What is the UV index reading in September in Silverthorne?

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

Average temperature in September
Silverthorne, CO

Average temperature in September - Silverthorne, CO
  • Average high temperature in September: 59.7°F

The warmest month (with the highest average high temperature) is July (67.6°F).
The month with the lowest average high temperature is December (22.8°F).

  • Average low temperature in September: 33.6°F

The month with the highest average low temperature is July (39.7°F).
The coldest month (with the lowest average low temperature) is January (1.2°F).

Average pressure in September
Silverthorne, CO

Average pressure in September - Silverthorne, CO
  • Average pressure in September: 30.05"Hg

The month with the highest atmospheric pressure is January (30.2"Hg).
The months with the lowest atmospheric pressure are April and May (29.94"Hg).

Average wind speed in September
Silverthorne, CO

Average wind speed in September - Silverthorne, CO
  • Average wind speed in September: 5.2mph

The windiest month (with the highest average wind speed) is February (6.6mph).
The calmest month (with the lowest average wind speed) is August (4.8mph).

Average humidity in September
Silverthorne, CO

Average humidity in September - Silverthorne, CO
  • Average humidity in September: 58%

The month with the highest relative humidity is February (88%).
The month with the lowest relative humidity is June (53%).

Average rainfall in September
Silverthorne, CO

Average rainfall in September - Silverthorne, CO
  • Average rainfall in September: 0.91"

The wettest month (with the highest rainfall) is May (2.05").
The driest month (with the least rainfall) is September (0.91").

Average rainfall days in September
Silverthorne, CO

Average rainfall days in September - Silverthorne, CO
  • Average rainfall days in September: 9.8 days

The month with the highest number of rainy days is July (17.6 days).
The month with the least rainy days is November (3.6 days).

Average snowfall in September
Silverthorne, CO

Average snowfall in September - Silverthorne, CO
  • Average snowfall in September: 0.94"

The month with the highest snowfall is March (14.61").
The month with the least snowfall is August (0.24").

Average snowfall days in September
Silverthorne, CO

Average snowfall days in September - Silverthorne, CO
  • Average snowfall days in September: 3.5 days

The month with the highest number of snowfall days is March (20.3 days).
The month with the least snowfall days is July (0.6 days).

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

Average daylight in September / Average sunshine in September - Silverthorne, CO
  • Average daylight in September: 12h and 2min

The month with the longest days is June (Average daylight: 14h and 54min).
The month with the shortest days is December (Average daylight: 9h and 24min).

  • Average sunshine in September: 10h and 5min

The month with the most sunshine is June (Average sunshine: 11h and 36min).
The month with the least sunshine is February (Average sunshine: 5h and 30min).

Average sunshine days in September
Silverthorne, CO

Average sunshine days in September - Silverthorne, CO
  • Average sunshine days in September: 15 days

The month with the most sunshine days is November (17.5 days).
The month with the least sunshine days is April (7.4 days).

Average UV index in September
Silverthorne, CO

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

The months with the highest UV index are July and August (UV index 4).
The months with the lowest UV index are February and December (UV index 1).

Average cloud cover in September
Silverthorne, CO

Average cloud cover in September - Silverthorne, CO
  • Average cloud cover in September: 19

The month with the most cloud cover is February (Cloud cover 51).
The month with the least cloud cover is June (Cloud cover 17).

Average visibility in September
Silverthorne, CO

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

The months with the highest visibility are June, July, August, September and October (6mi).
The months with the lowest visibility are January, February, March, April and December (4mi).

Silverthorne, Colorado, USA

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