Lewis and Clark County (Helena)
September
Weather in Lewis and Clark County, Montana for September 2027
Your guide to Lewis and Clark County weather in September - trends and predictions
With an average of 5 rainy days, Lewis and Clark County experiences minimal rainfall in September.
Is September a good time to visit Lewis and Clark County? check out the best time to travel to Lewis and Clark County page.
✨ Is September a good time to visit Lewis and Clark County? – Ask the AI Weatherman
Rain 🌧️
More
25
Dry days
5
Rainy days
0
Snow days
22°/8°
Temperatures
15 km/h
Avg max wind
51 %
Avg humidity
Lewis and Clark County Weather September
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Temperatures trend during September in Lewis and Clark County
See the weather trend as well as the moving average line
September weather in Lewis and Clark County day by day
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| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 |  Sunny | 30° /12° | 0.2 mm | 5 | |
| Sept. 2 |  Light rain | 29° /13° | 2.8 mm | 6 | |
| Sept. 3 | Sunny | 26° /10° | 0 mm | 5 | |
| Sept. 4 |  Partly cloudy | 22° /10° | 0 mm | 5 | |
| Sept. 5 | Sunny | 22° /7° | 0 mm | 6 | |
| Sept. 6 | Sunny | 24° /8° | 0 mm | 5 | |
| Sept. 7 |  Thundery outbreaks possible | 22° /9° | 35.9 mm | 4 | |
| Sept. 8 | Sunny | 21° /9° | 0 mm | 6.2 | |
| Sept. 9 | Thundery outbreaks possible | 24° /9° | 0 mm | 6 | |
| Sept. 10 | Thundery outbreaks possible | 28° /11° | 0 mm | 6 | |
| Sept. 11 |  Moderate rain | 21° /10° | 13.8 mm | 4 | |
| Sept. 12 | Thundery outbreaks possible | 20° /7° | 0 mm | 3 | |
| Sept. 13 |  Overcast | 20° /6° | 0.8 mm | 5.7 | |
| Sept. 14 | Partly cloudy | 19° /7° | 0.1 mm | 5.6 | |
| Sept. 15 | Overcast | 17° /6° | 0 mm | 5 | |
| Sept. 16 |  Cloudy | 19° /7° | 0 mm | 5.5 | |
| Sept. 17 | Sunny | 23° /7° | 0 mm | 5.4 | |
| Sept. 18 | Light rain | 23° /9° | 2.6 mm | 4 | |
| Sept. 19 | Light rain | 18° /9° | 7.9 mm | 3 | |
| Sept. 20 | Sunny | 23° /8° | 0 mm | 5.1 | |
| Sept. 21 | Moderate rain | 23° /8° | 10.4 mm | 5 | |
| Sept. 22 | Light rain | 20° /7° | 7.7 mm | 4 | |
| Sept. 23 | Sunny | 23° /7° | 0.1 mm | 4.8 | |
| Sept. 24 | Sunny | 26° /8° | 0 mm | 4.7 | |
| Sept. 25 | Sunny | 27° /10° | 0.2 mm | 4.6 | |
| Sept. 26 | Sunny | 17° /6° | 0 mm | 4.5 | |
| Sept. 27 | Sunny | 20° /3° | 0.1 mm | 4 | |
| Sept. 28 | Sunny | 22° /7° | 0.1 mm | 4.4 | |
| Sept. 29 |  Patchy rain possible | 24° /8° | 1.8 mm | 4 | |
| Sept. 30 | Cloudy | 20° /10° | 0.1 mm | 4 | |
| Next | |||||
Important Notice
Our weather forecast for Lewis and Clark 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 Lewis and Clark County forecast closer to your planned date for the most up-to-date weather information.
Change Month
Lewis and Clark County in September - FAQ
What are the expected maximum and minimum temperatures in Lewis and Clark County during September?
Enjoy moderate daytime temperatures of up to 22° and cooler nights around 8°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in Lewis and Clark County during September?
Moderate rainfall is anticipated in Lewis and Clark County during September, with a total of 84.3 mm spread over approximately 5 days. Considering plans for rainy days is advisable.
What are the typical wind conditions in Lewis and Clark County during September?
The average wind speed in Lewis and Clark County during September is 15 km/h, suggesting breezy to windy conditions, depending on your activities.
September rainfall patterns in Lewis and Clark County
Explore the daily rainfall trends and prepare for Lewis and Clark Countys September weather 💧
Typically, Lewis and Clark County has 5 rainy days in September with a total of 84.3 mm of rainfall.
UV exposure in Lewis and Clark County during September
Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
Top locations in Lewis and Clark County
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