Frost Dates for Blackhawk, CA

Based on data from Mt Diablo Junction weather station, 4 miles away

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. March 8
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. December 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 March 28
First Fall Frost December 9

Hard Freeze (28°F)

Last Spring Hard Freeze February 8
First Fall Hard Freeze January 16
37.82°N, -121.91°W © OpenStreetMap

Growing Season

289 Days March 8 to December 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 9b

Avg. annual minimum: 25 to 30°F (−4 to −1°C)

Learn more

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

Csb Warm-Summer Mediterranean

Warm, dry summers and mild, wet winters. Similar to hot-summer Mediterranean but cooler. Great for a wide range of vegetables and fruit trees with moderate water needs.

Köppen climate map

Temperature

40° 60° 80°
48°
High: 54°F
Avg: 48°F
Low: 42°F
Jan
48°
High: 55°F
Avg: 48°F
Low: 42°F
Feb
50°
High: 58°F
Avg: 50°F
Low: 43°F
Mar
53°
High: 62°F
Avg: 53°F
Low: 44°F
Apr
59°
High: 68°F
Avg: 59°F
Low: 49°F
May
66°
High: 76°F
Avg: 66°F
Low: 55°F
Jun
72°
High: 83°F
Avg: 72°F
Low: 62°F
Jul
72°
High: 83°F
Avg: 72°F
Low: 61°F
Aug
70°
High: 80°F
Avg: 70°F
Low: 60°F
Sep
63°
High: 72°F
Avg: 63°F
Low: 54°F
Oct
53°
High: 60°F
Avg: 53°F
Low: 46°F
Nov
47°
High: 53°F
Avg: 47°F
Low: 41°F
Dec
Avg High Avg Temp Avg Low

Precipitation

0" 3" 6" 8.2"
7.7"
7.66"
Jan
7.4"
7.44"
Feb
6.7"
6.74"
Mar
4.5"
4.51"
Apr
3.0"
2.95"
May
0.0"
0.00"
Jun
0.0"
0.00"
Jul
0.0"
0.00"
Aug
0.0"
0.00"
Sep
2.6"
2.62"
Oct
6.0"
5.99"
Nov
8.2"
8.19"
Dec

Sunrise / Sunset

4a7a10a1p4p7p10pNoonJanFebMarAprMayJunJulAugSepOctNovDec9.5h10.5h11.5h13h14h14.5h14.5h13.5h12h11h10h9.5h
Jan: 7:11 AM – 4:49 PM · 9h 39m
Feb: 6:42 AM – 5:18 PM · 10h 35m
Mar: 6:09 AM – 5:51 PM · 11h 42m
Apr: 5:30 AM – 6:30 PM · 12h 59m
May: 4:59 AM – 7:01 PM · 14h 03m
Jun: 4:42 AM – 7:18 PM · 14h 37m
Jul: 4:49 AM – 7:11 PM · 14h 23m
Aug: 5:16 AM – 6:44 PM · 13h 28m
Sep: 5:53 AM – 6:07 PM · 12h 14m
Oct: 6:30 AM – 5:30 PM · 10h 60m
Nov: 7:03 AM – 4:57 PM · 9h 55m
Dec: 7:18 AM – 4:42 PM · 9h 23m
Daylight Longest: 14h 38m · Shortest: 9h 22m

Nearby Stations

Concord Buchanan Fld, CA January 9 - December 14 Concord Wwtp, CA January 7 - December 19 Antioch Pumping Plt #3, CA January 12 - December 19 Martinez Wtp, CA February 28 - November 22 Livermore Muni AP, CA February 27 - December 1 Livermore, CA February 15 - December 2

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