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Will it freeze in Johnstown in the next 7 nights?
No overnight lows at or below 32°F are forecast in Johnstown during the next 7 nights in the available NWS frost forecast.
Tonight: forecast low 35°F. Frost possible.
NWS forecast period: Thu, Nov 5, 6:00 PM MST to Fri, Nov 6, 6:00 AM MST.
6 of the next 7 nights are forecast at 36°F or colder, cold enough for frost on exposed plants.
- Tonight 35°F Frost possible · Mostly Cloudy
- Fri, Nov 6 34°F Frost possible · Mostly Clear
- Sat, Nov 7 34°F Frost possible · Mostly Clear
- Sun, Nov 8 36°F Frost possible · Clear
- Mon, Nov 9 37°F Above 36°F · Mostly Clear
- Tue, Nov 10 36°F Frost possible · Partly Cloudy
- Wed, Nov 11 35°F Frost possible · Partly Cloudy
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 Johnstown
The median first fall hard-freeze date (28°F) is October 10, from NOAA’s 1991–2020 Climate Normals at Loveland 2N. 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 | May 11 · May 22 · Jun 4 | Sep 8 · Sep 22 · Oct 4 | 122 days |
| 32°F freeze | Apr 30 · May 10 · May 22 | Sep 15 · Oct 1 · Oct 13 | 142 days |
| 28°F hard freeze | Apr 17 · May 2 · May 14 | Sep 22 · Oct 10 · Oct 22 | 159 days |
Average high temperature by month
1991–2020 normals at Loveland 2N
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 Johnstown, CO come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Loveland 2N (station USC00055236, elevation 5,080 ft), 13 mi from Johnstown. 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 Johnstown
| City | Distance | Last spring frost | First fall frost |
|---|---|---|---|
| Milliken, CO | 2.5 mi | May 2 | Oct 8 |
| Berthoud, CO | 3.1 mi | May 7 | Oct 5 |
| Mead, CO | 6.8 mi | May 7 | Oct 5 |
| Evans, CO | 9.3 mi | May 2 | Oct 8 |
| Greeley, CO | 11 mi | May 2 | Oct 8 |
| Firestone, CO | 11 mi | May 7 | Oct 5 |
| Loveland, CO | 11 mi | May 10 | Oct 1 |
| Windsor, CO | 12 mi | May 3 | Oct 6 |
| Longmont, CO | 14 mi | May 7 | Oct 5 |
| Severance, CO | 14 mi | May 3 | Oct 6 |
Frequently asked questions
When is the last frost in Johnstown?
On average, the last spring frost (32°F) in Johnstown is around May 10. In about 1 year in 10 it comes after May 22, and in 9 years in 10 it comes after April 30.
When is the first frost in Johnstown?
The first fall frost (32°F) usually arrives around October 1. There’s a 10% chance of a freeze by September 15 and a 90% chance by October 13.
Can it frost in Johnstown 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 May 22.
What growing zone is Johnstown?
Johnstown is in USDA Plant Hardiness Zone 5b (average annual extreme minimum temperature −15 to −10°F), based on the 2023 USDA map for ZIP code 80534. See growing zones in Colorado.
More: all Colorado frost dates · Colorado growing zones · frost vs. freeze