Frost dates for Phoenix Sky Harbor, 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
January 5
typical year
Safe to plant
January 22
frost is over in 9 of 10 years
First fall frost
January 3
typical year
Growing season
365 days
frost-free, typical year
Frost watch this week
Tonight's and the next six nights' lows from the National Weather Service forecast for the station's location. Frost: 32°F or colder. Possible frost: 33–36°F, mostly in low spots on clear, still nights.
When to plant
Counted from this page's frost dates. Warm-season crops wait for the safe-to-plant date.
| Crop | Start indoors | Plant outside | Fall planting |
|---|---|---|---|
| Cool-season crops | |||
| Peas | Season usually too short. Try a quick variety or row covers. | ||
| Spinach | – | Nov 24 – Dec 15 | Nov 8 – 22 |
| Lettuce | – | Dec 8 – 29 | Nov 8 – 22 |
| Radishes | – | Dec 8 – Jan 19 | Nov 22 – Dec 6 |
| Onions | – | Dec 8 – 22 | – |
| Potatoes | Season usually too short. Try a quick variety or row covers. | ||
| Carrots | – | Dec 15 – Jan 5 | Oct 11 – 25 |
| Beets | – | Dec 8 – 22 | Oct 25 – Nov 8 |
| Kale | Oct 27 – Nov 10 | Dec 8 – 22 | Oct 25 – Nov 8 |
| Broccoli | Oct 27 – Nov 10 | Dec 22 – Jan 5 | Oct 25 – Nov 8 |
| Cabbage | Oct 13 – 27 | Dec 8 – 22 | Oct 25 – Nov 8 |
| Garlic | – | – | Nov 22 – Dec 13 |
| Warm-season crops | |||
| Tomatoes | Season usually too short. Try a quick variety or row covers. | ||
| Peppers | Season usually too short. Try a quick variety or row covers. | ||
| Cucumbers | Season usually too short. Try a quick variety or row covers. | ||
| Zucchini | Season usually too short. Try a quick variety or row covers. | ||
| Pumpkins | Season usually too short. Try a quick variety or row covers. | ||
| Green beans | Season usually too short. Try a quick variety or row covers. | ||
| Sweet corn | Season usually too short. Try a quick variety or row covers. | ||
| Basil | Season usually too short. Try a quick variety or row covers. | ||
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 10 | Half of years | 9 years in 10 | |
|---|---|---|---|
| Spring frost after | January 22 | January 5 | December 19 |
| Fall frost before | December 18 | January 3 | January 21 |
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 n/a (n/a in a late year), and the first one in fall around n/a.
Where these dates come from
NOAA weather station PHOENIX SKY HARBOR INTL AP, AZ US (USW00023183), 1991–2020 climate normals. It's the nearest station for 15 zip codes, all within 10 miles:
85003, 85004, 85006, 85008, 85012, 85013, 85014, 85015, 85016, 85017, 85018, 85019, 85026, 85034, 85040
Planting dates follow common university extension advice; your local extension service can fine-tune them for your soil and microclimate.