Frost Dates: First and last frost dates for Stewart Mountain, AZ
ℹ️ How to read these charts for the spring
As spring unfolds, the risk of frost gradually decreases each day until your tender plants are finally safe. The probabilities shown in the chart help you make smart decisions about when to plant.
While frost typically forms at 32°F, tender plants can be damaged even when temperatures are slightly higher. Air temperatures are often measured several feet above the ground, but temperatures at plant level can be several degrees colder. Protected areas like porches help by blocking radiational cooling. Given these variables, we consider 36°F the "caution zone" for frost-sensitive plants.
Key dates for your spring planting:
- By April 14, you have a 90% chance of being frost-free — this is your "safe date" for planting tender crops
- Around March 12, there's a 50/50 chance of frost — check weather forecasts carefully if planting now
- Before February 17, there's still an 80% risk of frost — too early for tomatoes and other tender plants unless you're prepared to protect them
If the 10-day forecast shows no temperatures below 40°F, you might safely plant earlier than the above dates suggest. Many gardeners watch for this weather window to get a head start on the growing season.
| Temperature | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| Last 16° | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| Last 20° | Dec 31 | Dec 18 | -- | -- | -- | -- | -- | -- | -- |
| Last 24° | Jan 25 | Jan 7 | Dec 18 | -- | -- | -- | -- | -- | -- |
| Last 28° | Mar 2 | Feb 16 | Feb 6 | Jan 29 | Jan 20 | Jan 12 | Jan 2 | Dec 19 | -- |
| Last 32° | Mar 18 | Mar 7 | Feb 27 | Feb 20 | Feb 13 | Feb 7 | Jan 31 | Jan 23 | Jan 12 |
| Last 36° | Apr 14 | Apr 3 | Mar 25 | Mar 18 | Mar 12 | Mar 5 | Feb 26 | Feb 17 | Feb 6 |
ℹ️ How to read these charts for the fall
As summer ends in Stewart Mountain, AZ, nighttime temperatures begin to drop, and your risk of frost increases with each passing day. Knowing when to expect frost helps you harvest sensitive crops and extend your growing season with protection methods.
The chart below shows the probability of experiencing specific temperatures on various dates. Here's what this means for your garden:
These probabilities help you time your end-of-season harvests and know when to apply protective measures like row covers, cloches, or cold frames to extend your harvest.
| Temperature | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| First 16° | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| First 20° | Dec 20 | Jan 7 | -- | -- | -- | -- | -- | -- | -- |
| First 24° | Dec 13 | Dec 22 | Jan 3 | -- | -- | -- | -- | -- | -- |
| First 28° | Nov 20 | Nov 30 | Dec 7 | Dec 14 | Dec 20 | Dec 26 | Jan 3 | Jan 15 | -- |
| First 32° | Nov 11 | Nov 17 | Nov 21 | Nov 24 | Nov 27 | Nov 30 | Dec 4 | Dec 8 | Dec 13 |
| First 36° | Nov 1 | Nov 7 | Nov 11 | Nov 14 | Nov 17 | Nov 20 | Nov 23 | Nov 27 | Dec 3 |
📍 Frost Dates for other nearby locations
- Mormon Flat, AZ 8.2 mi
- Bartlett Dam, AZ 17.0 mi
- Tempe Asu, AZ 27.4 mi
- Chandler Heights, AZ 27.4 mi
- Carefree, AZ 28.8 mi
- Roosevelt, AZ 28.8 mi
- Phoenix Ap, AZ 32.7 mi
- Superior, AZ 37.4 mi
- South Phoenix, AZ 38.1 mi
- Sacaton, AZ 38.1 mi
Or enter a new zipcode:
Data is provided by the NOAA National Centers for Environmental Information.