When to plant in Waterloo, IA
USDA Zone 5aWaterloo, Iowa frost dates, USDA zone, and a full-year planting calendar, drawn from the nearest NOAA station and tuned to the local season.
Zone 5a means Waterloo sees real winter cold, but a good range of perennials survive; the frost dates above govern when annual vegetables go out.
The average first fall frost in Waterloo is now 7 days later than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
WATERLOO MUNI AP · 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 Waterloo’s own odds, recorded at WATERLOO MUNI AP.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 17 | May 6 | Apr 23 | Sep 16 | Sep 30 | Oct 11 |
| 32°F | May 10 | Apr 27 | Apr 11 | Sep 26 | Oct 10 | Oct 21 |
| 28°F | May 2 | Apr 16 | Apr 3 | Oct 6 | Oct 20 | Oct 31 |
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 Waterloo, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 36 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.
Waterloo planting FAQ
When is the last spring frost in Waterloo, IA?
Waterloo's average last spring frost falls near April 27 — the 50% mark at 32°F in the 1991–2020 normals. Hold tender transplants until the risk has passed, then plant out.
When is the first fall frost in Waterloo, IA?
The first fall frost in Waterloo typically arrives around October 10 (50% probability at 32°F). Harvest or protect frost-sensitive crops before then.
What hardiness zone is Waterloo in?
Waterloo is in USDA hardiness zone 5a. In zone 5a, winters are cold — pick cold-hardy varieties and protect tender crops.
How long is the growing season in Waterloo?
There are roughly 166 frost-free days in Waterloo (a moderate growing season), running from the average last frost around April 27 to the first fall frost near October 10.
When should I plant tomatoes in Waterloo?
In Waterloo, start tomato seeds indoors around March 2–March 16, then transplant seedlings outdoors around May 4 once the danger of frost has passed.
Never miss a window in Waterloo
An email when it’s time to start seeds, transplant, and sow — timed to Waterloo’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Cedar Falls · 9 km
- Waverly · 27 km
- Marshalltown · 68 km
- Marion · 80 km
- Cedar Rapids · 81 km
- Mason City · 100 km
- North Liberty · 103 km
- Newton · 105 km
Frost dates recorded at WATERLOO MUNI AP, 8 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 Waterloo, IA — Frost Dates & Zone 5a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USW00094910. Retrieved from https://blissgarden.com/iowa/waterloo.