When to plant in Mountain House, CA
USDA Zone 9bHere are the average frost dates, USDA hardiness zone, and a month-by-month planting calendar for Mountain House, California — all computed from Mountain House's nearest NOAA weather station.
With about 325 frost-free days, Mountain House supports back-to-back plantings; stagger sowings every few weeks to keep beds productive spring through fall. In zone 9b, frost is a minor factor for Mountain House — most perennials thrive, and annual vegetables can go out early and stay late.
The average last spring frost in Mountain House is now 11 days earlier than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
TRACY PUMPING PLT · 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 Mountain House’s own odds, recorded at TRACY PUMPING PLT.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | Mar 24 | Feb 21 | Jan 22 | Nov 13 | Nov 29 | Dec 13 |
| 32°F | Feb 17 | Jan 19 | Dec 25 | Nov 26 | Dec 10 | Jan 7 |
| 28°F | Jan 22 | Jan 1 | Dec 12 | Dec 4 | Dec 22 | Jan 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 Mountain House, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 26 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.
Mountain House planting FAQ
When is the last spring frost in Mountain House, CA?
Plan for the last spring frost in Mountain House around January 19 (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 Mountain House, CA?
Expect Mountain House's first fall frost near December 10 — a 50% chance of 32°F by that date. Bring in or cover tender crops ahead of it.
What hardiness zone is Mountain House in?
Mountain House is in USDA hardiness zone 9b. In zone 9b, winters are mild — many tender perennials overwinter here.
How long is the growing season in Mountain House?
Mountain House has about 325 frost-free days — a long growing season — between the average last spring frost (January 19) and first fall frost (December 10).
When should I plant tomatoes in Mountain House?
For Mountain House, sow tomatoes indoors about November 24–December 8 and move the seedlings out around January 26, after the last spring frost.
Never miss a window in Mountain House
An email when it’s time to start seeds, transplant, and sow — timed to Mountain House’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Tracy · 9 km
- Discovery Bay · 15 km
- Lathrop · 20 km
- Livermore · 22 km
- Brentwood · 24 km
- Country Club · 27 km
- Manteca · 27 km
- Oakley · 28 km
Frost dates recorded at TRACY PUMPING PLT, 4 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 Mountain House, CA — Frost Dates & Zone 9b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00049001. Retrieved from https://blissgarden.com/california/mountain-house.