Frost Dates for Arrowrock Dam, ID

Elevation: 986 m

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. April 28
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. October 14

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 4
First Fall Frost October 8

Hard Freeze (28°F)

Last Spring Hard Freeze April 6
First Fall Hard Freeze October 27
43.59°N, 115.92°W © OpenStreetMap

Growing Season

169 Days April 28 to October 14

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 6b

Avg. annual minimum: −5 to 0°F

Learn more

Köppen Climate

The Köppen climate classification system categorizes climates based on temperature and precipitation patterns.
Dsa Hot-Summer Continental (Dry Summer)

Hot, dry summers and cold, wet winters. A continental version of Mediterranean climate. Summer irrigation is essential; cold-hardy crops grow well in the wet season.

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
January37°30°22°
February43°34°25°
March53°42°32°
April61°49°37°
May71°58°44°
June80°65°50°
July92°75°59°
August91°74°57°
September80°65°49°
October65°51°38°
November48°39°30°
December37°30°24°

Precipitation

Precipitation table
Average monthly precipitation (inches)
MonthPrecipitation
January2.4
February2.0
March2.7
April2.5
May2.5
June2.1
July0.1
August0.0
September1.3
October2.0
November2.1
December2.2

Sunrise / Sunset

Daylight Longest: 15h 15m · Shortest: 8h 45m
Sunrise and sunset table
Sunrise, sunset, and daylight on the 15th of each month (local solar time)
Month Sunrise Sunset Daylight
January7:27 AM4:33 PM9h 06m
February6:52 AM5:08 PM10h 16m
March6:11 AM5:49 PM11h 39m
April5:24 AM6:36 PM13h 13m
May4:44 AM7:16 PM14h 31m
June4:23 AM7:37 PM15h 14m
July4:32 AM7:28 PM14h 56m
August5:06 AM6:54 PM13h 48m
September5:52 AM6:08 PM12h 17m
October6:37 AM5:23 PM10h 46m
November7:17 AM4:43 PM9h 26m
December7:37 AM4:23 PM8h 46m

Nearby Stations

Boise Lucky Peak Dam, ID April 30 - October 22 Boise Air Terminal, ID April 24 - October 21 Boise 7 N, IDMay 17 - October 12 Idaho City, ID June 17 - September 5 Emmett 2 E, ID April 30 - October 17 Nampa Sugar Factory, ID April 29 - October 13

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