Frost dates for 86004 — Flagstaff, AZ
Last spring frostMay 13median date
First fall frostOct 6median date
Growing season146 daysfrost-free
Hardiness zone6bZone 6b
How Flagstaff compares
- In 8 years out of 10, the last spring frost in Flagstaff falls between April 27 and May 30, a 33-day window. The first fall frost falls between September 26 and October 21.
- The median last frost is 27 days later than the Arizona median of Apr 16.
- Its 146-day growing season is longer than 20% of the 193 Arizona places with a regular frost season (state median 197 days).
- The last frost is 21 days later than the zone 6b median of Apr 22. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 6b chart.
- The weather station records an average of 161 nights a year at or below 32°F.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 27 |
| 50% (median) | May 13 |
| 10% (safe for tender plants) | May 30 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 26 |
| 50% (median) | October 6 |
| 90% (late) | October 21 |
Frost here means 32°F (0°C). A median date means half of years have their last frost earlier and half later.
Planting calendar for Flagstaff, AZ
Frost dates for 86004 — Flagstaff, AZ — last frost May 13, first frost Oct 6, zone 6b. whenisthelastfrost.com
Crop
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Start indoors: Feb 18 to Mar 4Transplant outside: Apr 15 to Apr 29
Start indoors: Mar 4 to Mar 18Transplant outside: May 27 to Jun 10
Start indoors: Mar 4 to Mar 18Transplant outside: May 27 to Jun 10
Start indoors: Mar 18 to Apr 1Transplant outside: May 20 to Jun 3
Start indoors: Mar 18 to Apr 1Transplant outside: Apr 22 to May 6Sow outdoors: Apr 15 to May 20Plant for fall: Aug 11 to Sep 8
Start indoors: Mar 18 to Apr 1Transplant outside: Apr 15 to Apr 29Sow outdoors: Apr 15 to Apr 29Plant for fall: Jul 28 to Aug 18
Start indoors: Mar 18 to Apr 1Transplant outside: Apr 29 to May 13Plant for fall: Jun 30 to Jul 21
Start indoors: Mar 18 to Apr 1Transplant outside: Apr 22 to May 6Plant for fall: Jun 30 to Jul 21
Start indoors: Mar 18 to Apr 1Transplant outside: Apr 29 to May 13Plant for fall: Jun 30 to Jul 21
Start indoors: Apr 1 to Apr 15Transplant outside: Jun 3 to Jun 17Sow outdoors: Jun 3 to Jun 17
Start indoors: Apr 1 to Apr 15Transplant outside: May 20 to Jun 3
Sow outdoors: Apr 1 to Apr 22Plant for fall: Jul 14 to Aug 4
Sow outdoors: Apr 1 to Apr 22Plant for fall: Aug 11 to Sep 1
Sow outdoors: Apr 8 to May 20Plant for fall: Aug 25 to Sep 15
Start indoors: Apr 15 to Apr 22Transplant outside: May 27 to Jun 3Sow outdoors: May 20 to Jun 3Plant for fall: Jul 21 to Aug 4
Start indoors: Apr 15 to Apr 22Sow outdoors: May 20 to Jun 3Plant for fall: Jul 28 to Aug 11
Start indoors: Apr 15 to Apr 22Sow outdoors: May 20 to Jun 3
Start indoors: Apr 15 to Apr 22Transplant outside: May 27 to Jun 10
Sow outdoors: Apr 22 to May 20Plant for fall: Jul 14 to Jul 28
Sow outdoors: Apr 22 to May 20Plant for fall: Jul 28 to Aug 11
Sow outdoors: Apr 22 to May 13
Sow outdoors: Apr 29 to May 27Plant for fall: Jul 28 to Aug 11
Sow outdoors: Apr 29 to May 20Plant for fall: Aug 11 to Sep 1
Sow outdoors: May 20 to Jun 10Plant for fall: Jul 21 to Aug 4
Sow outdoors: May 20 to Jun 3
Transplant outside: May 27 to Jun 17
Plant for fall: Sep 22 to Oct 27
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Flagstaff, AZ
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 18 – Mar 4 | Apr 15 – Apr 29 | — | — |
| Peppers | Mar 4 – Mar 18 | May 27 – Jun 10 | — | — |
| Eggplant | Mar 4 – Mar 18 | May 27 – Jun 10 | — | — |
| Tomatoes | Mar 18 – Apr 1 | May 20 – Jun 3 | — | — |
| Lettuce | Mar 18 – Apr 1 | Apr 22 – May 6 | Apr 15 – May 20 | Aug 11 – Sep 8 |
| Kale | Mar 18 – Apr 1 | Apr 15 – Apr 29 | Apr 15 – Apr 29 | Jul 28 – Aug 18 |
| Broccoli | Mar 18 – Apr 1 | Apr 29 – May 13 | — | Jun 30 – Jul 21 |
| Cabbage | Mar 18 – Apr 1 | Apr 22 – May 6 | — | Jun 30 – Jul 21 |
| Cauliflower | Mar 18 – Apr 1 | Apr 29 – May 13 | — | Jun 30 – Jul 21 |
| Okra | Apr 1 – Apr 15 | Jun 3 – Jun 17 | Jun 3 – Jun 17 | — |
| Basil | Apr 1 – Apr 15 | May 20 – Jun 3 | — | — |
| Peas | — | — | Apr 1 – Apr 22 | Jul 14 – Aug 4 |
| Spinach | — | — | Apr 1 – Apr 22 | Aug 11 – Sep 1 |
| Radishes | — | — | Apr 8 – May 20 | Aug 25 – Sep 15 |
| Cucumbers | Apr 15 – Apr 22 | May 27 – Jun 3 | May 20 – Jun 3 | Jul 21 – Aug 4 |
| Zucchini & Summer Squash | Apr 15 – Apr 22 | — | May 20 – Jun 3 | Jul 28 – Aug 11 |
| Winter Squash & Pumpkins | Apr 15 – Apr 22 | — | May 20 – Jun 3 | — |
| Melons & Watermelon | Apr 15 – Apr 22 | May 27 – Jun 10 | — | — |
| Carrots | — | — | Apr 22 – May 20 | Jul 14 – Jul 28 |
| Beets | — | — | Apr 22 – May 20 | Jul 28 – Aug 11 |
| Potatoes | — | — | Apr 22 – May 13 | — |
| Swiss Chard | — | — | Apr 29 – May 27 | Jul 28 – Aug 11 |
| Cilantro | — | — | Apr 29 – May 20 | Aug 11 – Sep 1 |
| Green Beans | — | — | May 20 – Jun 10 | Jul 21 – Aug 4 |
| Sweet Corn | — | — | May 20 – Jun 3 | — |
| Sweet Potatoes | — | May 27 – Jun 17 | — | — |
| Garlic | — | — | — | Sep 22 – Oct 27 |
Dates come from the median frost dates and common extension-service timing. Adjust for your soil temperature, microclimate and the varieties you grow.
About these dates
Based on 1991–2020 NOAA climate normals for the Walnut Canyon Nm, AZ weather station, 8 km away (elevation 6,696 ft (2,041 m)).
ZIP codes in Flagstaff: 86001 86002 86003 86004 86005 86011
Frost dates near Flagstaff
- Bellemont Jun 21 · Sep 17
- Munds Park Jun 10 · Sep 27
- Parks Jun 21 · Sep 17
- Mormon Lake Jun 10 · Sep 27
- Sedona Apr 1 · Nov 17
- Leupp Apr 14 · Oct 25
- Gray Mountain Apr 7 · Nov 3
- Cornville Mar 30 · Nov 10
Frequently asked questions
When is the last frost in Flagstaff, AZ?
The median last spring frost in Flagstaff, AZ is May 13. There is still about a 10% chance of frost after May 30, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Flagstaff, AZ?
The median first fall frost is October 6, with about a 10% chance of frost before September 26.
How long is the growing season in Flagstaff, AZ?
About 146 days between the median last spring frost and first fall frost.
What planting zone is Flagstaff, AZ?
Flagstaff, AZ is in USDA hardiness zone 6b.