Frost Dates for Union, MO

Elevation: 165 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 11
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 23

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 April 17
First Fall Frost October 18

Hard Freeze (28°F)

Last Spring Hard Freeze March 31
First Fall Hard Freeze November 3
38.44°N, 91.00°W © OpenStreetMap

Growing Season

195 Days April 11 to October 23

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.
Dfa Hot-Summer Continental

Hot summers and cold winters with year-round precipitation. Moderate growing season supports warm-season crops like tomatoes, peppers, and corn. Winter protection extends the harvest.

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
January43°33°23°
February48°37°26°
March59°47°35°
April70°58°45°
May78°67°55°
June86°75°63°
July91°79°67°
August89°78°66°
September82°69°57°
October70°58°46°
November57°46°35°
December46°37°27°

Precipitation

Precipitation table
Average monthly precipitation (inches)
MonthPrecipitation
January3.8
February4.3
March6.4
April6.8
May5.5
June6.9
July8.0
August6.6
September6.9
October6.7
November6.6
December5.0

Sunrise / Sunset

Daylight Central Time (CT) Longest: 14h 41m · Shortest: 9h 19m
Sunrise and sunset table
Sunrise, sunset, and daylight on the 15th of each month (Central Time (CT))
Month Sunrise Sunset Daylight
January7:25 AM5:01 PM9h 36m
February7:02 AM5:35 PM10h 34m
March7:23 AM7:05 PM11h 42m
April6:34 AM7:35 PM13h 01m
May5:58 AM8:03 PM14h 05m
June5:44 AM8:24 PM14h 40m
July5:57 AM8:23 PM14h 26m
August6:23 AM7:53 PM13h 30m
September6:51 AM7:06 PM12h 14m
October7:20 AM6:18 PM10h 58m
November6:53 AM4:45 PM9h 52m
December7:20 AM4:40 PM9h 20m

Nearby Stations

Washington, MO April 8 - October 25 Rosebud, MOApril 27 - October 13 St Louis Sprt Of S L AP, MO April 12 - October 23 Weldon Spring NWS, MO April 10 - October 26 Warrenton 1 N, MO April 14 - October 23 St Charles 7 Ssw, MO April 4 - October 29

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