Frost Dates for San Luis, AZ 85349

Last spring frost February 23 · First fall frost December 20 · 300 frost-free days · USDA Zone 10a

Frost probability for 85349

Frost10%50%90%
Spring (last frost)March 1February 23January 23
Fall (first frost)November 25December 20January 15

Dates come from NOAA 1971–2000 freeze probabilities at the nearest reporting station (77.7 km away); the 50% date is the median year.

Frost dates by ZIP code in San Luis, AZ

ZIPLast spring frost (50%)First fall frost (50%)Zone
85349February 23December 2010a
85336January 24December 2010a

Month by month in San Luis

MonthWhat to do
JanuaryStart herbs, basil, and squash indoors (4–6 weeks before frost). Direct sow peas, spinach, and lettuce if soil is workable.
FebruaryLast frost around February 23. Transplant cold-hardy crops (broccoli, kale, cabbage). Harden off tomato and pepper seedlings.
MarchFrost has passed. Transplant tomatoes, peppers, and basil outdoors. Direct sow beans, cucumbers, squash, and zucchini.
AprilSuccession plant lettuce and greens. Keep beds weeded and watered consistently.
MayHarvest regularly to encourage production. Monitor for pests and disease.
JuneMidsummer: harvest beans, zucchini, cucumbers. Start brassica seeds indoors for fall.
JulyDirect sow carrots and beets for fall harvest. Start fall broccoli and kale indoors.
AugustDirect sow carrots and beets for fall harvest. Start fall broccoli and kale indoors.
SeptemberDirect sow carrots and beets for fall harvest. Start fall broccoli and kale indoors.
OctoberDirect sow carrots and beets for fall harvest. Start fall broccoli and kale indoors.
NovemberFirst fall frost approaching (around December 20). Transplant fall brassicas. Sow spinach, arugula, and radishes.
DecemberFirst frost around December 20. Harvest tomatoes and peppers before frost. Cover cold-hardy crops with row covers to extend the season.

What grows in a 300-day season

Frequently Asked Questions

What is the last frost date for San Luis, AZ (ZIP 85349)?

The median last spring frost date for San Luis, AZ (ZIP code 85349) is around February 23. This is the 50th-percentile date — meaning half of all years see frost end before this date. Use the 10% and 90% dates to understand the full range of risk in your area.

What is the first fall frost date in San Luis, AZ?

The median first fall frost date for San Luis, AZ is around December 20. Plan to harvest or protect frost-sensitive crops like tomatoes and peppers at least a week before this date to avoid losses.

How long is the growing season in San Luis, AZ?

The frost-free growing season in San Luis is about 300 days. This window — from your last spring frost to your first fall frost — is when warm-season vegetables thrive. Cold-hardy crops like kale, spinach, and peas can extend your season by weeks on either side.

What USDA hardiness zone is San Luis, AZ?

Based on frost date patterns, San Luis falls approximately in 10a. USDA hardiness zones are determined by average annual minimum winter temperatures and guide both plant selection and planting timing for your location.

When should I start tomatoes indoors in San Luis, AZ?

Start tomato seeds indoors 6–8 weeks before your last frost date (around February 23). For San Luis, that's roughly December 29 to January 12. Transplant outdoors 1–2 weeks after your last frost.

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