Weather Almanac: Great Falls, MT 59405

🗓️ Historical norms for September 2026

September avg. precipitation
🌧️ 1.26"
September days below freezing
📉 ≈1.5 days
Average September lows ≈43.8°F
USDA Zone
4b
Annual extreme lows -25°F to -20°F
Last Spring Frost (36°F)
🌷 Jun 6
First Fall Frost (36°F)
🍂 Sep 11
Tue. September 1  

🌅 6:44 a.m.

H: ≈79.6°F

L: ≈49.7°F

🌇 8:04 p.m.

Wed. September 2  

🌅 6:45 a.m.

H: ≈79.1°F

L: ≈49.3°F

🌇 8:02 p.m.

Thu. September 3  

🌅 6:46 a.m.

H: ≈78.7°F

L: ≈48.9°F

🌇 8:00 p.m.

Fri. September 4  

🌅 6:48 a.m.

H: ≈78.2°F

L: ≈48.6°F

🌇 7:58 p.m.

Sat. September 5  

🌅 6:49 a.m.

H: ≈77.7°F

L: ≈48.2°F

🌇 7:56 p.m.

Sun. September 6  

🌅 6:50 a.m.

H: ≈77.2°F

L: ≈47.8°F

🌇 7:54 p.m.

Mon. September 7 Labor Day  

🌅 6:52 a.m.

H: ≈76.6°F

L: ≈47.4°F

🌇 7:52 p.m.

Tue. September 8  

🌅 6:53 a.m.

H: ≈76.1°F

L: ≈47.0°F

🌇 7:50 p.m.

Wed. September 9  

🌅 6:54 a.m.

H: ≈75.5°F

L: ≈46.5°F

🌇 7:48 p.m.

Thu. September 10  

🌅 6:56 a.m.

H: ≈75.0°F

L: ≈46.1°F

🌇 7:46 p.m.

Fri. September 11  

🌅 6:57 a.m.

H: ≈74.4°F

L: ≈45.7°F

🌇 7:44 p.m.

Sat. September 12  

🌅 6:58 a.m.

H: ≈73.8°F

L: ≈45.2°F

🌇 7:42 p.m.

Sun. September 13  

🌅 7:00 a.m.

H: ≈73.2°F

L: ≈44.8°F

🌇 7:40 p.m.

Mon. September 14 Holy Cross  

🌅 7:01 a.m.

H: ≈72.7°F

L: ≈44.3°F

🌇 7:38 p.m.

Tue. September 15  

🌅 7:02 a.m.

H: ≈72.1°F

L: ≈43.9°F

🌇 7:36 p.m.

Wed. September 16  

🌅 7:04 a.m.

H: ≈71.5°F

L: ≈43.5°F

🌇 7:34 p.m.

Thu. September 17  

🌅 7:05 a.m.

H: ≈70.9°F

L: ≈43.0°F

🌇 7:32 p.m.

Fri. September 18  

🌅 7:06 a.m.

H: ≈70.4°F

L: ≈42.6°F

🌇 7:30 p.m.

Sat. September 19  

🌅 7:08 a.m.

H: ≈69.8°F

L: ≈42.2°F

🌇 7:28 p.m.

Sun. September 20  

🌅 7:09 a.m.

H: ≈69.2°F

L: ≈41.8°F

🌇 7:26 p.m.

Mon. September 21  

🌅 7:10 a.m.

H: ≈68.7°F

L: ≈41.4°F

🌇 7:24 p.m.

Tue. September 22 Autumn Equinox  

🌅 7:12 a.m.

H: ≈68.2°F

L: ≈41.0°F

🌇 7:22 p.m.

Wed. September 23  

🌅 7:13 a.m.

H: ≈67.7°F

L: ≈40.6°F

🌇 7:20 p.m.

Thu. September 24  

🌅 7:14 a.m.

H: ≈67.2°F

L: ≈40.2°F

🌇 7:18 p.m.

Fri. September 25  

🌅 7:16 a.m.

H: ≈66.7°F

L: ≈39.9°F

🌇 7:16 p.m.

Sat. September 26 🌕

🌅 7:17 a.m.

H: ≈66.2°F

L: ≈39.5°F

🌇 7:14 p.m.

Sun. September 27  

🌅 7:18 a.m.

H: ≈65.8°F

L: ≈39.2°F

🌇 7:12 p.m.

Mon. September 28  

🌅 7:20 a.m.

H: ≈65.4°F

L: ≈38.9°F

🌇 7:10 p.m.

Tue. September 29  

🌅 7:21 a.m.

H: ≈65.0°F

L: ≈38.6°F

🌇 7:08 p.m.

Wed. September 30  

🌅 7:22 a.m.

H: ≈64.6°F

L: ≈38.3°F

🌇 7:06 p.m.


Temperature climatic data from weather station: GREAT FALLS 16ST (USC00243749)

Precipitation climatic data from weather station: GREAT FALLS 16ST (USC00243749)

Agricultural climatic data from weather station: GREAT FALLS WFO (USC00243753)