September weather forecast
Grand Junction, CO

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The scenic Grand Junction in Colorado with the iconic Colorado River and high hills nearby
The scenic Grand Junction in Colorado with the iconic Colorado River and high hills nearby

Weather in September

In September, Grand Junction ushers in the first hints of autumn as temperatures start to decrease. Weather conditions take a gentle turn from the peak summer heat, with temperatures dropping to a pleasant 76.5°F (24.7°C) at most. Though autumn's arrival is gradual, the days start to shorten, but still offer substantial daylight. While the rainfall continues its rhythm, nature starts preparing for the winter with the first snowfall in sight. Atmospheric pressure stabilizes, predicting consistent weather.

Temperature

In the transition to September, Grand Junction observes a minor drop in the average high-temperature, shifting from a warm 84.2°F (29°C) in August to a still moderately hot 76.5°F (24.7°C). Throughout the month of September, Grand Junction observes a dramatic downturn from the daytime peak temperatures, expecting an average low of 53.1°F (11.7°C).

Humidity

The average relative humidity in September is 39%.

Rainfall

In Grand Junction, in September, during 7.3 rainfall days, 0.63" (16mm) of precipitation is typically accumulated. In Grand Junction, during the entire year, the rain falls for 93.6 days and collects up to 8.46" (215mm) of precipitation.

Snowfall

May through September are months without snowfall.

Daylight

In Grand Junction, the average length of the day in September is 12h and 26min.
On the first day of the month, sunrise is at 6:43 am and sunset at 7:44 pm. On the last day of September, sunrise is at 7:10 am and sunset at 6:57 pm MDT.

Sunshine

In September, the average sunshine is 11h.

UV index

The average daily maximum UV index in September in Grand Junction, Colorado, is 5. A UV Index value of 3 to 5 symbolizes a moderate health risk from unprotected exposure to Sun's UV rays for ordinary individuals.
Note: A daily maximum UV index of 5 in September translates into the following instructions:
Exercise prevention - Precautions against solar damage are endorsed. The Sun's radiation is especially intense around midday; try to stay in shade during this period. Limit sun-induced ocular harm with sunglasses that feature UVA and UVB filtration.
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Frequently asked questions

What is the temperature in September in Grand Junction?

Grand Junction in September has an average high-temperature of 76.5°F (24.7°C) and an average low-temperature of 53.1°F (11.7°C).

What is the average humidity in September in Grand Junction?

The average relative humidity in September in Grand Junction, Colorado, is 39%.

How much does it rain in Grand Junction in September?

In Grand Junction, Colorado, during September, the rain falls for 7.3 days and regularly aggregates up to 0.63" (16mm) of precipitation.

When it does not snow in Grand Junction?

In Grand Junction, Colorado, snow does not fall in May through September.

Does it snow in Grand Junction in September?

In Grand Junction, in September, it doesn't snow. In October, it regularly snows.

What is the average length of the day in September in Grand Junction?

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

What time are sunrise and sunset in September in Grand Junction?

On the first day of September in Grand Junction, sunrise is at 6:43 am and sunset at 7:44 pm. On the last day of the month, sunrise is at 7:10 am and sunset at 6:57 pm MDT.

How long on average sun shines in September in Grand Junction?

In September, the average sunshine duration in Grand Junction is 11h.

What is the UV index intensity in September in Grand Junction?

In September, the average daily maximum UV index in Grand Junction is 5. A UV Index value of 3 to 5 symbolizes a medium hazard to health from exposure to Sun's UV rays.
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
Grand Junction, CO

Average temperature in September - Grand Junction, CO
  • Average high temperature in September: 76.5°F

The warmest month (with the highest average high temperature) is July (86.9°F).
The month with the lowest average high temperature is January (34.9°F).

  • Average low temperature in September: 53.1°F

The month with the highest average low temperature is July (60.4°F).
The coldest month (with the lowest average low temperature) is January (18.3°F).

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Average pressure in September
Grand Junction, CO

Average pressure in September - Grand Junction, CO
  • Average pressure in September: 30"Hg

The month with the highest atmospheric pressure is January (30.27"Hg).
The months with the lowest atmospheric pressure are May and June (29.9"Hg).

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Average wind speed in September
Grand Junction, CO

Average wind speed in September - Grand Junction, CO
  • Average wind speed in September: 6.2mph

The windiest month (with the highest average wind speed) is June (7.5mph).
The calmest month (with the lowest average wind speed) is January (4.2mph).

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Average humidity in September
Grand Junction, CO

Average humidity in September - Grand Junction, CO
  • Average humidity in September: 39%

The month with the highest relative humidity is January (78%).
The month with the lowest relative humidity is June (29%).

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Average rainfall in September
Grand Junction, CO

Average rainfall in September - Grand Junction, CO
  • Average rainfall in September: 0.63"

The wettest month (with the highest rainfall) is March (1.06").
The driest month (with the least rainfall) is June (0.51").

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Average rainfall days in September
Grand Junction, CO

Average rainfall days in September - Grand Junction, CO
  • Average rainfall days in September: 7.3 days

The month with the highest number of rainy days is March (10.4 days).
The month with the least rainy days is November (5.5 days).

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Average snowfall in September
Grand Junction, CO

Average snowfall in September - Grand Junction, CO
  • Average snowfall in September: 0"

The month with the highest snowfall is December (3.74").
The months with the least snowfall are May, June, July, August and September (0").

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Average snowfall days in September
Grand Junction, CO

Average snowfall days in September - Grand Junction, CO
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is January (7.9 days).
The months with the least snowfall days are May, June, July, August and September (0 days).

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Average daylight in September /
Average sunshine in September
Grand Junction, CO

Average daylight in September / Average sunshine in September - Grand Junction, 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 30min).

  • Average sunshine in September: 11h and 0min

The month with the most sunshine is June (Average sunshine: 12h and 0min).
The month with the least sunshine is January (Average sunshine: 6h and 18min).

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Average sunshine days in September
Grand Junction, CO

Average sunshine days in September - Grand Junction, CO
  • Average sunshine days in September: 19.3 days

The month with the most sunshine days is November (22.3 days).
The month with the least sunshine days is February (15.8 days).

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Average UV index in September
Grand Junction, CO

Average UV index in September - Grand Junction, CO
  • Average UV index in September: 5

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, November and December (UV index 2).

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Average cloud cover in September
Grand Junction, CO

Average cloud cover in September - Grand Junction, CO
  • Average cloud cover in September: 11

The month with the most cloud cover is January (Cloud cover 31).
The months with the least cloud cover are June and September (Cloud cover 11).

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Average visibility in September
Grand Junction, CO

Average visibility in September - Grand Junction, CO
  • Average visibility in September: 6mi

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

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Grand Junction, Colorado, USA

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