Frost Report

All states Arizona

Frost dates for Mc Nary, AZ

When the last spring frost and first fall frost usually come, and when to plant, from 30 years of NOAA weather records.

Last spring frost

May 20

typical year

Safe to plant

June 4

frost is over in 9 of 10 years

First fall frost

October 11

typical year

Growing season

142 days

frost-free, typical year

When to plant

Counted from this page's frost dates. Warm-season crops wait for the safe-to-plant date.

CropStart indoorsPlant outsideFall planting
Cool-season crops
Peas – Apr 22 – May 6 –
Spinach – Apr 8 – 29 Aug 16 – 30
Lettuce – Apr 22 – May 13 Aug 16 – 30
Radishes – Apr 22 – Jun 3 Aug 30 – Sep 13
Onions – Apr 22 – May 6 –
Potatoes – Apr 29 – May 13 –
Carrots – Apr 29 – May 20 Jul 19 – Aug 2
Beets – Apr 22 – May 6 Aug 2 – 16
Kale Mar 11 – 25 Apr 22 – May 6 Aug 2 – 16
Broccoli Mar 11 – 25 May 6 – 20 Aug 2 – 16
Cabbage Feb 25 – Mar 11 Apr 22 – May 6 Aug 2 – 16
Garlic – – Aug 30 – Sep 20
Warm-season crops
Tomatoes Apr 9 – 23 Jun 4 – 18 –
Peppers Apr 2 – 16 Jun 11 – 25 –
Cucumbers – Jun 4 – 25 –
Zucchini – Jun 4 – Jul 2 –
Pumpkins – Jun 4 – 25 –
Green beans – Jun 4 – Aug 2 –
Sweet corn – Jun 4 – Jul 2 –
Basil Apr 30 – May 14 Jun 11 – 18 –

Onions: from sets. Green beans: until 10 weeks before the first fall frost. Garlic: harvest next summer.

The year at a glance

Start indoors Plant outside Fall planting

The chance of frost, by date

1 year in 10Half of years9 years in 10
Spring frost after June 4May 20May 5
Fall frost before September 29October 11October 24

Frost here means 32°F or colder. Read across: in 1 year in 10, spring frost carries on past the first date, which is why that date is the safe-to-plant date.

Hard freeze (28°F)

A hard freeze kills most garden plants, even hardy ones. The last one in spring usually comes around May 6 (May 23 in a late year), and the first one in fall around October 22.

Where these dates come from

NOAA weather station MC NARY 2N, AZ US (USC00025412), 1991–2020 climate normals. It's the nearest station for 2 zip codes, all within 13 miles:

85930, 85940

Planting dates follow common university extension advice; your local extension service can fine-tune them for your soil and microclimate.