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Will it freeze in Ottawa in the next 7 nights?
The earliest overnight low at or below 32°F in the available NWS frost forecast is Fri, Nov 6: 32°F (Fri, Nov 6, 6:00 PM CST to Sat, Nov 7, 6:00 AM CST).
Tonight: forecast low 40°F. Above 36°F.
NWS forecast period: Thu, Nov 5, 6:00 PM CST to Fri, Nov 6, 6:00 AM CST.
2 of the next 7 nights are forecast at 36°F or colder, cold enough for frost on exposed plants.
- Tonight 40°F Above 36°F · Mostly Cloudy
- Fri, Nov 6 32°F Freeze · Partly Cloudy
- Sat, Nov 7 35°F Frost possible · Mostly Clear
- Sun, Nov 8 38°F Above 36°F · Clear
- Mon, Nov 9 42°F Above 36°F · Clear
- Tue, Nov 10 45°F Above 36°F · Mostly Clear
- Wed, Nov 11 45°F Above 36°F · Mostly Clear
Overnight lows from the National Weather Service forecast for this location. This covers the available forecast window, not the first freeze of the whole season. Frost can form above 32°F on clear, calm nights.
Frost and freeze probabilities
Freeze dates shift from year to year. Spring percentages describe the chance of a freeze after the stated date; fall percentages describe the chance of a freeze by that date. The 10% spring date is the cautious one: a later freeze happens about 1 year in 10.
These dates describe historical probabilities, not this year’s forecast or the earliest and latest possible freezes. Different weather stations or probability thresholds can produce different published dates for the same city.
Average first hard freeze in Ottawa
The median first fall hard-freeze date (28°F) is October 30, from NOAA’s 1991–2020 Climate Normals at Ottawa. This is the 50% probability date, not a forecast for this year.
| Temperature | Last spring date 90% · 50% · 10% chance of a later freeze | First fall date 10% · 50% · 90% chance of an earlier freeze | Season |
|---|---|---|---|
| 36°F frost possible | Apr 15 · Apr 29 · May 10 | Sep 26 · Oct 9 · Oct 22 | 162 days |
| 32°F freeze | Apr 5 · Apr 18 · May 1 | Oct 3 · Oct 20 · Nov 1 | 183 days |
| 28°F hard freeze | Mar 24 · Apr 8 · Apr 22 | Oct 16 · Oct 30 · Nov 11 | 203 days |
Average high temperature by month
1991–2020 normals at Ottawa
Average low temperature by month
Months with lows near or below freezing carry frost risk
Where these frost dates come from
The frost dates for Ottawa, KS come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Ottawa (station USC00146128, elevation 905 ft), 1.4 mi from Ottawa. Local conditions (valleys, hilltops, distance to water, city heat) can shift frost dates by days or weeks. The hardiness zone is from the 2023 USDA Plant Hardiness Zone Map (USDA ARS and Oregon State University PRISM). See our methodology.
Frost dates near Ottawa
| City | Distance | Last spring frost | First fall frost |
|---|---|---|---|
| Paola, KS | 22 mi | Apr 13 | Oct 21 |
| Gardner, KS | 24 mi | Apr 13 | Oct 24 |
| Eudora, KS | 25 mi | Apr 21 | Oct 17 |
| Lawrence, KS | 25 mi | Apr 12 | Oct 28 |
| Spring Hill, KS | 26 mi | Apr 13 | Oct 24 |
| De Soto, KS | 28 mi | Apr 13 | Oct 24 |
| Olathe, KS | 31 mi | Apr 10 | Oct 29 |
| Louisburg, KS | 32 mi | Apr 13 | Oct 21 |
| Lenexa, KS | 35 mi | Apr 10 | Oct 29 |
| Tonganoxie, KS | 37 mi | Apr 21 | Oct 17 |
Frequently asked questions
When is the last frost in Ottawa?
On average, the last spring frost (32°F) in Ottawa is around April 18. In about 1 year in 10 it comes after May 1, and in 9 years in 10 it comes after April 5.
When is the first frost in Ottawa?
The first fall frost (32°F) usually arrives around October 20. There’s a 10% chance of a freeze by October 3 and a 90% chance by November 1.
Can it frost in Ottawa after the last frost date?
Yes. Frost can form on clear, calm nights even when the air stays above 32°F. Temperatures of 36°F or lower, cold enough for frost on exposed plants, have a 50% chance of occurring after April 29.
What growing zone is Ottawa?
Ottawa is in USDA Plant Hardiness Zone 6b (average annual extreme minimum temperature −5 to 0°F), based on the 2023 USDA map for ZIP code 66067. See growing zones in Kansas.
More: all Kansas frost dates · Kansas growing zones · frost vs. freeze