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%) A 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%) A 50% chance that the first fall frost has occurred by this date. Plan to harvest or protect tender plants before this date. September 22

30% Probability

Only 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

Hardiness 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

Learn more

Köppen Climate

The 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

Avg High Avg Temp Avg Low Light Frost (32°F) Hard Frost (28°F)
Temperature table
Average monthly temperatures (°F)
Month Avg High Avg Temp Avg Low
January35°22°10°
February38°25°13°
March48°34°20°
April59°45°31°
May68°55°41°
June76°62°49°
July86°70°54°
August86°69°52°
September74°58°42°
October60°45°31°
November47°34°21°
December37°25°13°

Precipitation

Precipitation table
Average monthly precipitation (inches)
MonthPrecipitation
January1.9
February1.7
March2.0
April2.8
May3.7
June3.5
July2.9
August3.0
September3.5
October2.4
November1.9
December1.9

Sunrise / Sunset

Daylight Mountain Time (MT) Longest: 15h 49m · Shortest: 8h 11m
Sunrise and sunset table
Sunrise, sunset, and daylight on the 15th of each month (Mountain Time (MT))
Month Sunrise Sunset Daylight
January8:14 AM4:50 PM8h 36m
February7:38 AM5:37 PM9h 59m
March7:45 AM7:20 PM11h 35m
April6:41 AM8:05 PM13h 24m
May5:51 AM8:47 PM14h 57m
June5:29 AM9:16 PM15h 47m
July5:45 AM9:11 PM15h 26m
August6:24 AM8:30 PM14h 06m
September7:07 AM7:27 PM12h 20m
October7:51 AM6:25 PM10h 34m
November7:38 AM4:38 PM8h 60m
December8:12 AM4:25 PM8h 12m

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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