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Whatcom County (North Cascades National Park)
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United States weather

Weather in Whatcom County, Washington for September 2027

Your guide to Whatcom County weather in September - trends and predictions

    Temperatures

  • In general, the average temperature in Whatcom County at the beginning of September is 20.1 °F. As the month progressed, temperatures tended to significantly cool down, reaching an average of 14.6 °F by the end of September.

    • Rain 🌧️

  • Whatcom County in September brings notable rainfall, with an average of 16 rainy days and a total precipitation of 83.8 mm.

    • More

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Average dry days
14
Dry days
Average rainy days
16
Rainy days
Average snowy days
0
Snow days
Average temperatures
19°/8°
Temperatures
Average wind speed
8 km/h
Avg max wind
Average humidity
63 %
Avg humidity

Whatcom County Weather September

Move between months or click on a day
August
October
Sun.Mon.Tue.Wed.Thu.Fri.Sat.
1
Patchy rain possible
25°
2
Moderate or heavy rain shower
19°
3
Moderate rain at times
17°
4
Patchy rain possible
19°
5
Heavy rain at times
19°
6
Overcast
23°
7
Patchy rain possible
19°
8
Partly cloudy
24°
9
Overcast
25°
10
Patchy rain possible
22°
11
Patchy rain possible
21°
12
Overcast
25°
13
Moderate rain at times
13°
14
Patchy rain possible
15°
15
Moderate rain at times
14°
16
Sunny
22°
17
Cloudy
25°
18
Sunny
23°
19
Overcast
25°
20
Sunny
25°
21
Overcast
22°
22
Overcast
17°
23
Overcast
15°
24
Overcast
20°
25
Moderate or heavy rain shower
15°
26
Patchy rain possible
14°
27
Overcast
17°
28
Overcast
15°
29
Moderate or heavy rain shower
9°
30
Cloudy
12°

Temperatures trend during September in Whatcom County

See the weather trend as well as the moving average line

September weather in Whatcom County day by day

Click on a date for more information
August October
Date Weather Temperatures Rain UV More
Sept. 1 Patchy rain possible
Patchy rain possible
 25° /13° 1.2 mm 1
Sept. 2 Moderate or heavy rain shower
Moderate or heavy rain shower
 19° /10° 10.3 mm 2
Sept. 3 Moderate rain at times
Moderate rain at times
 17° /9° 1.6 mm 3
Sept. 4 Patchy rain possible
Patchy rain possible
 19° /8° 3.1 mm 1
Sept. 5 Heavy rain at times
Heavy rain at times
 19° /9° 2.5 mm 4
Sept. 6 Overcast
Overcast
 23° /9° 0 mm 6
Sept. 7 Patchy rain possible
Patchy rain possible
 19° /10° 0.7 mm 3
Sept. 8 Partly cloudy
Partly cloudy
 24° /9° 0 mm 5
Sept. 9 Overcast
Overcast
 25° /12° 0 mm 3
Sept. 10 Patchy rain possible
Patchy rain possible
 22° /12° 0.3 mm 5
Sept. 11 Patchy rain possible
Patchy rain possible
 21° /8° 0.1 mm 2
Sept. 12 Overcast
Overcast
 25° /11° 0 mm 2
Sept. 13 Moderate rain at times
Moderate rain at times
 13° /11° 5.8 mm 1
Sept. 14 Patchy rain possible
Patchy rain possible
 15° /9° 0.9 mm 1
Sept. 15 Moderate rain at times
Moderate rain at times
 14° /9° 3.4 mm 2
Sept. 16 Sunny
Sunny
 22° /6° 0 mm 4
Sept. 17 Cloudy
Cloudy
 25° /8° 0 mm 4
Sept. 18 Sunny
Sunny
 23° /9° 0 mm 4
Sept. 19 Overcast
Overcast
 25° /8° 0 mm 3
Sept. 20 Sunny
Sunny
 25° /8° 0 mm 4
Sept. 21 Overcast
Overcast
 22° /10° 0 mm 3
Sept. 22 Overcast
Overcast
 17° /9° 0 mm 1
Sept. 23 Overcast
Overcast
 15° /6° 0 mm 2
Sept. 24 Overcast
Overcast
 20° /6° 0.5 mm 1
Sept. 25 Moderate or heavy rain shower
Moderate or heavy rain shower
 15° /6° 18 mm 1
Sept. 26 Patchy rain possible
Patchy rain possible
 14° /5° 1.3 mm 1
Sept. 27 Overcast
Overcast
 17° /3° 0 mm 3
Sept. 28 Overcast
Overcast
 15° /5° 0.9 mm 1
Sept. 29 Moderate or heavy rain shower
Moderate or heavy rain shower
 9° /6° 30.8 mm 0
Sept. 30 Cloudy
Cloudy
 12° /4° 1.2 mm 2
Next
Important Notice
Our weather forecast for Whatcom County in September is based on the analysis of historical data rather than real-time forecast models. While this provides a general overview, weather conditions can change. We recommend that you check the Whatcom County forecast closer to your planned date for the most up-to-date weather information.
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Whatcom County in September - FAQ

What are the expected maximum and minimum temperatures in Whatcom County during September?
Enjoy moderate daytime temperatures of up to 19° and cooler nights around 8°. Ideal for a range of outdoor activities, from hiking to city tours.

How much rainfall should be expected in Whatcom County during September?
Moderate rainfall is anticipated in Whatcom County during September, with a total of 83.8 mm spread over approximately 16 days. Considering plans for rainy days is advisable.

What are the typical wind conditions in Whatcom County during September?
The average wind speed in Whatcom County during September is 8 km/h, suggesting breezy to windy conditions, depending on your activities.

September rainfall patterns in Whatcom County

Explore the daily rainfall trends and prepare for Whatcom Countys September weather 💧
Typically, Whatcom County has 16 rainy days in September with a total of 83.8 mm of rainfall.

UV exposure in Whatcom County during September

Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
Top locations in Whatcom County
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North Cascades National Park
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Location coordinates Where is Whatcom County?

Get accurate weather forecasts for Whatcom County, located at latitude 48.833 and longitude -121.347. Stay updated with localized weather information tailored for Whatcom County.

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