When is the first frost near Scottsdale? University of Arizona (UA) Cooperative Extension puts the average first frost in Maricopa County between November 21 (Buckeye) and December 12 (central Phoenix), and the average last frost between February 7 and April 3. That means late November through February is the window to watch.
How do you protect plants from frost? Water first, then cover sensitive plants with frost cloth or sheets, never plastic, draped all the way to the ground, and remove sheets in the morning. Wrap the trunks of young citrus, and don't prune frost damage until spring.
Data note: Dates and methods come from UA Cooperative Extension's "Frost Protection" (AZ1002) and a UA Master Gardener frost and freeze guide. Plant cold-hardiness varies by species and variety; confirm for your own plants.
Frost Dates and Cold Facts for the Valley
- Average first frost (Maricopa County): Nov. 21 in Buckeye to Dec. 12 in central Phoenix
- Average last frost: Feb. 7 in central Phoenix to April 3 in Mesa
- Normal winter lows: in the 40s, per UA
- Record low: 16°F in Phoenix on Jan. 7, 1913
- Coldest time of night: around daybreak
- Riskiest nights: calm and clear, with no clouds to hold heat in
- Cold air flows downhill and pools at the lowest point in a yard
UA's practical tip: keep a thermometer in your yard and compare it with the reported forecast. If you consistently run a few degrees colder than the airport, you'll know to act sooner.
Which Plants Need Protection?
Usually Need Covering
- Citrus, especially young trees. A UA Master Gardener guide says temperatures approaching freezing call for covering citrus to the ground, and below 28°F a safe heat source may be needed
- Sago palm (not a true palm): very cold-sensitive
- Mexican fence post cactus: protect from freeze
- Totem pole cactus: hardy only to about 30°F
- Columnar cacti tips, where the growing points are
Usually Ride It Out
- Most agaves and prickly pear (verify your species)
- Red yucca and hedgehog cactus
- Senita cactus to about 18°F, organ pipe to about 24°F
- Most palms: generally hardy, but verify your variety
- Lantana goes dormant at freezing and comes back; prune it to green stems in February
How to Protect Plants From Frost: UA's Method
Before a Cold Night
- Water sensitive plants. Hydrated plants suffer less frost injury
- Keep soil bare, firm and moist under citrus; mulch or loose soil holds less heat
- Don't over-protect all winter. Hardened-off plants handle cold better
Covering
- Use frost cloth, sheets, blankets, burlap or paper, never plastic
- Drape to the ground at least out to the drip line; don't gather it at the trunk
- Use a frame so fabric doesn't touch foliage
- Frost cloth protects to about 30°F, some fabrics to about 20°F
- Remove sheets and blankets each morning when it reaches about 50°F underneath. Many frost cloths can stay on longer
Extra Heat (Hard Freezes)
- A 100-watt incandescent bulb in an approved outdoor fixture under the cover, kept away from trunk and branches
- A trickle of water at the base of a tree late at night and early morning, for no more than three nights in a row
- Wrap young citrus trunks in loose layers to the ground; this can stay on mid-November to mid-February
What Doesn't Work
- Smudge pots, large fires and spray-on anti-frost products. UA says no commercial chemical has withstood scientific scrutiny
After a Frost: Be Patient
- Don't prune frost-damaged woody growth until spring growth begins
- Damaged leaves still insulate the canopy
- Damage is often less severe than it first looks
- On grafted citrus, if it dies back below the graft, regrowth will be rootstock, not your variety
This lines up with our Arizona tree trimming guide, which saves citrus pruning for February through April. If your lawn goes "blonde" after a cold snap, our overseeding guide explains why.
“A December freeze is the one week of the year when 85250 neighbors are out at dusk draping frost cloth over lemon trees. If you're listing in winter, keep a roll of frost cloth in the garage and cover the bougainvillea and young citrus before cold nights. Buyers notice a yard that came through winter green.”
— Elizabeth Vijan, Tackett Team, eXp Realty
FAQ: Frost Protection in Scottsdale
When is the first frost in the Phoenix area?
Average first frost runs Nov. 21 to Dec. 12 across Maricopa County, per UA.
How do I protect plants from frost overnight in Arizona?
Water, then drape frost cloth or sheets (not plastic) to the ground; uncover sheets in the morning.
Should I cover my citrus trees for frost?
Yes, especially young trees: cover near freezing and wrap trunks mid-November to mid-February.
Should I prune frost-damaged plants?
Wait until spring growth starts, then remove dead wood.
Buying or Selling an 85250 Home This Winter?
From winter curb appeal to sorting out which yard items matter on an inspection, I'll help you make smart, local calls.
Elizabeth Vijan | Tackett Team, eXp Realty
Chaparral Park Resident & 85250 Real Estate Expert
Talk to Elizabeth About Your Move · Call or text 602-885-7752
Sources: UA Cooperative Extension: Frost Protection (AZ1002) · UA Cooperative Extension: Frost Protection (AZ1002, PDF) · UA SaddleBrooke Master Gardeners: Frost/freeze plant guide (PDF)
Disclaimer: General information, not horticultural advice for a specific plant. Use outdoor-rated fixtures and keep heat sources away from foliage and fabric. Information deemed reliable but not guaranteed. Equal Housing Opportunity.
