Frost Dates for Fort Benton, MT

Based on data from Ft Benton weather station, 1 miles away

Elevation: 2621 ft

Frost Dates

Last Spring Frost (50%) iA 50% chance that the last spring frost has already passed by this date. Most gardeners use this as their primary planting guide. May 15
First Fall Frost (50%) iA 50% chance that the first fall frost has occurred by this date. Plan to harvest or protect tender plants before this date. September 22
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

30% Probability iOnly a 30% chance of frost remaining by this date. Use these dates for a safer planting window, especially for tender plants sensitive to cold.

Last Spring Frost May 20
First Fall Frost September 17

Hard Freeze (28°F)

Last Spring Hard Freeze May 4
First Fall Hard Freeze October 1
47.82°N, -110.67°W © OpenStreetMap

Growing Season

130 Days May 15 to September 22

USDA Hardiness Zone iHardiness zones indicate which perennial plants can survive winter in your area. For annual vegetables, frost dates and growing season length matter more than hardiness zone.

Zone 4a

Avg. annual minimum: −30 to −25°F (−34 to −32°C)

Learn more

Köppen Climate iThe Köppen climate classification system categorizes climates based on temperature and precipitation patterns.

BSk Cold Semi-Arid (Steppe)

Cool to cold with low rainfall and wide temperature swings. Common in the western Great Plains and central Asia. Short growing seasons benefit from season extension techniques.

Köppen climate map

Temperature

10° 30° 50° 70° 90°
22°
High: 35°F
Avg: 22°F
Low: 10°F
Jan
25°
High: 38°F
Avg: 25°F
Low: 13°F
Feb
34°
High: 48°F
Avg: 34°F
Low: 20°F
Mar
45°
High: 59°F
Avg: 45°F
Low: 31°F
Apr
55°
High: 68°F
Avg: 55°F
Low: 41°F
May
62°
High: 76°F
Avg: 62°F
Low: 49°F
Jun
70°
High: 86°F
Avg: 70°F
Low: 54°F
Jul
69°
High: 86°F
Avg: 69°F
Low: 52°F
Aug
58°
High: 74°F
Avg: 58°F
Low: 42°F
Sep
45°
High: 60°F
Avg: 45°F
Low: 31°F
Oct
34°
High: 47°F
Avg: 34°F
Low: 21°F
Nov
25°
High: 37°F
Avg: 25°F
Low: 13°F
Dec
32°F
28°F
Avg High Avg Temp Avg Low Light Frost (32°F) Hard Frost (28°F)

Precipitation

0" 1" 2" 3" 3.7"
1.9"
1.86"
Jan
1.7"
1.68"
Feb
2.0"
1.98"
Mar
2.8"
2.76"
Apr
3.7"
3.66"
May
3.5"
3.54"
Jun
2.9"
2.88"
Jul
3.0"
3.04"
Aug
3.5"
3.48"
Sep
2.4"
2.39"
Oct
1.9"
1.86"
Nov
1.9"
1.86"
Dec

Sunrise / Sunset

4a7a10a1p4p7p10pNoonJanFebMarAprMayJunJulAugSepOctNovDec8.5h10h11.5h13.5h15h16h15.5h14h12.5h10.5h9h8h
Jan: 8:14 AM – 4:50 PM · 8h 36m
Feb: 7:38 AM – 5:37 PM · 9h 59m
Mar: 7:45 AM – 7:20 PM · 11h 35m
Apr: 6:41 AM – 8:05 PM · 13h 24m
May: 5:51 AM – 8:47 PM · 14h 57m
Jun: 5:29 AM – 9:16 PM · 15h 47m
Jul: 5:45 AM – 9:11 PM · 15h 26m
Aug: 6:24 AM – 8:30 PM · 14h 06m
Sep: 7:07 AM – 7:27 PM · 12h 20m
Oct: 7:51 AM – 6:25 PM · 10h 34m
Nov: 7:38 AM – 4:38 PM · 8h 60m
Dec: 8:12 AM – 4:25 PM · 8h 12m
Daylight Mountain Time (MT) Longest: 15h 49m · Shortest: 8h 11m

Nearby Stations

Loma, MTMay 20 - September 19 Highwood 7 Ne, MT May 7 - October 2 Shonkin 7 S, MT May 24 - September 21 Geraldine, MT May 14 - September 26 Carter 14 W, MT May 23 - September 23 Rudyard 19s, MT May 23 - September 19

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