When to plant in Somerton, AZ
USDA Zone 10aEverything below — frost dates, hardiness zone, and what to plant when in Somerton, Arizona — is derived from the closest NOAA station with complete climate normals.
With about 354 frost-free days, Somerton supports back-to-back plantings; stagger sowings every few weeks to keep beds productive spring through fall. Somerton's nearest full-normals station sits about 16 km out, so treat these as a close estimate — local microclimate can nudge your first and last frost. In zone 10a, frost is a minor factor for Somerton — most perennials thrive, and annual vegetables can go out early and stay late.
Frost probability
YUMA QUARTERMASTER DEPOT · 1991–2020The date the last spring and first fall frost occur, by threshold and probability. A 90% date is later in spring — and earlier in fall — than a 10% date; the 50% · 32°F row is what most gardeners plan around. These are Somerton’s own odds, recorded at YUMA QUARTERMASTER DEPOT.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | Feb 28 | Jan 28 | Dec 25 | Nov 29 | Dec 16 | Jan 5 |
| 32°F | Feb 19 | Jan 8 | Dec 17 | Dec 11 | Dec 28 | Feb 7 |
| 28°F | Feb 16 | Jan 1 | Dec 19 | Dec 16 | Dec 31 | Feb 10 |
Download this table as CSV ↓ — every threshold and probability, plus this city’s planting-window dates.
What to plant now
TODAY · JULY 19Nothing new to sow or transplant outdoors in the next few weeks — a seasonal lull. Check the full-year calendar below for the next window.
Full-year planting calendar
Each bar is the exact window to take a planting action in Somerton, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
2 within 38 km · complete 32°F normalsWhen stations disagree by more than a few days, that spread is real microclimate variation — elevation, water, urban heat. Judge which station best matches your own yard.
Somerton planting FAQ
When is the last spring frost in Somerton, AZ?
Plan for the last spring frost in Somerton around January 8 (the date it has a 50% chance of a 32°F freeze). Anything frost-sensitive should go out after it.
When is the first fall frost in Somerton, AZ?
In Somerton, the first 32°F freeze of fall lands around December 28 on average. Time your last harvests and any season-extension cover before it.
What hardiness zone is Somerton in?
Somerton is in USDA hardiness zone 10a. In zone 10a, winters are mild — many tender perennials overwinter here.
How long is the growing season in Somerton?
Somerton has about 354 frost-free days — a long growing season — between the average last spring frost (January 8) and first fall frost (December 28).
When should I plant tomatoes in Somerton?
For Somerton, sow tomatoes indoors about November 13–November 27 and move the seedlings out around January 15, after the last spring frost.
Never miss a window in Somerton
An email when it’s time to start seeds, transplant, and sow — timed to Somerton’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reachFrost dates recorded at YUMA QUARTERMASTER DEPOT, 16 km from the city center · 1991–2020 NOAA climate normals · zone from the USDA/PRISM 2023 map. How we compute this.
BlissGarden. "When to Plant in Somerton, AZ — Frost Dates & Zone 10a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00029656. Retrieved from https://blissgarden.com/arizona/somerton.