When to plant in Arnold, MO
USDA Zone 7aEverything below — frost dates, hardiness zone, and what to plant when in Arnold, Missouri — is derived from the closest NOAA station with complete climate normals.
Arnold's nearest full-normals station sits about 22 km out, so treat these as a close estimate — local microclimate can nudge your first and last frost. In zone 7a, Arnold supports a wide range of perennials year-round; the frost dates above are what set your annual vegetable timing.
The average last spring frost in Arnold is now 7 days earlier than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
FESTUS · 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 Arnold’s own odds, recorded at FESTUS.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 8 | Apr 22 | Apr 5 | Oct 4 | Oct 17 | Oct 28 |
| 32°F | Apr 25 | Apr 9 | Mar 25 | Oct 14 | Oct 26 | Nov 8 |
| 28°F | Apr 15 | Mar 31 | Mar 12 | Oct 23 | Nov 5 | Nov 23 |
Download this table as CSV ↓ — every threshold and probability, plus this city’s planting-window dates.
What to plant now
TODAY · JULY 19Full-year planting calendar
Each bar is the exact window to take a planting action in Arnold, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 24 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.
Arnold planting FAQ
When is the last spring frost in Arnold, MO?
Plan for the last spring frost in Arnold around April 9 (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 Arnold, MO?
Expect Arnold's first fall frost near October 26 — a 50% chance of 32°F by that date. Bring in or cover tender crops ahead of it.
What hardiness zone is Arnold in?
Arnold is in USDA hardiness zone 7a. In zone 7a, winters are moderate — most common vegetables grow well in season.
How long is the growing season in Arnold?
Arnold has about 200 frost-free days — a moderate growing season — between the average last spring frost (April 9) and first fall frost (October 26).
When should I plant tomatoes in Arnold?
For Arnold, sow tomatoes indoors about February 12–February 26 and move the seedlings out around April 16, after the last spring frost.
Never miss a window in Arnold
An email when it’s time to start seeds, transplant, and sow — timed to Arnold’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reachFrost dates recorded at FESTUS, 22 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 Arnold, MO — Frost Dates & Zone 7a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00232850. Retrieved from https://blissgarden.com/missouri/arnold.