U.S. Frost Dates by Weather Station

NOAA station USC00055236 · Colorado

Frost Dates for Loveland, CO

NOAA weather station Loveland 2 N (USC00055236), Colorado · elevation 5080 ft (1548 m) · hardiness zone 5b*

  • Lower-risk planting dateafter May 22only 1 spring in 10 still has a frost later
  • Typical last frostMay 1050% chance of a frost after it
  • Typical first fall frostOctober 150% chance of a frost before it
  • Frost-free season142 daystypical year, 32°F
  • Hardiness zone5bcalculated*

The year at a glance

Frost season at Loveland, COSpring: a frost after April 30 in 9 years out of 10, after May 10 in half of the years, after May 22 in 1 year out of 10. Fall: the first frost comes before September 15 in 1 year out of 10, before October 1 in half of the years, before October 13 in 9 years out of 10. Typical frost-free season: 142 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 10First frost ~Oct 1Frost season at Loveland, COSpring: a frost after April 30 in 9 years out of 10, after May 10 in half of the years, after May 22 in 1 year out of 10. Fall: the first frost comes before September 15 in 1 year out of 10, before October 1 in half of the years, before October 13 in 9 years out of 10. Typical frost-free season: 142 days.JFMAMJJASONDLast frost ~May 10First frost ~Oct 1
frost likely chance fading 90% → 10% frost-free in a typical yearThe year at a glance. Blue: frost is likely; the gradient fades as the chance drops from 90% to 10%; green: the frost-free part of a typical year.

Frost dates (32°F)

Probability of frost, based on 25 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 22September 15
50% (typical)May 10October 1
90% (likely)April 30October 13
Frost-free season (32°F, 50% chance)
142 days
Hard frost (28°F), last in spring, 50% chance after
May 2
Hard frost (28°F), first in fall, 50% chance before
October 10

The last 15 years (2006–2020 normals)

Typical last frost May 9 (1 day earlier than the 30-year normal), typical first fall frost October 7 (6 days later). Frost-free season 148 days.

A shorter, more recent NOAA period. The 30-year normals above remain the main reference: 15 years carry more year-to-year noise.

Add these dates to your calendar Yearly reminders for the typical last frost, the lower-risk planting date and the typical first fall frost (.ics).

How the chance of frost changes with the date

Spring at Loveland: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 22, 20% May 18, 30% May 15, 40% May 13, 50% May 10, 60% May 8, 70% May 6, 80% May 3, 90% April 30. Observed last spring frost in recent years: 2021 May 12, 2022 May 23, 2023 April 25, 2024 May 22, 2025 May 4, 2026 May 7.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 22May 10Apr 302021: May 122022: May 232023: April 252024: May 222025: May 42026: May 7Fall at Loveland: chance of a frost before this dateFall, chance of a frost before the date: 10% September 15, 20% September 21, 30% September 25, 40% September 28, 50% October 1, 60% October 4, 70% October 7, 80% October 10, 90% October 13. Observed first fall frost in recent years: 2021 October 11, 2022 October 9, 2023 October 7, 2024 October 25, 2025 October 14.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Nov 1Sep 15Oct 1Oct 132021: October 112022: October 92023: October 72024: October 252025: October 14
Two charts, because spring and fall answer different questions: in spring, the chance that a frost still comes after a date; in fall, the chance that the first frost has already come before it. NOAA publishes these odds from 10% to 90%, so the lines stop there. ◆ marks the actual date in each recent year.

What actually happened in recent years

Observed dates of the last spring and first fall frost (32°F) at this station; ◆ marks them on the charts above
YearLast spring frostFirst fall frost
2021May 12October 11
2022May 23October 9
2023April 25October 7
2024May 22October 25
2025May 4October 14
2026May 7season not over yet

What these dates mean

Setting out tender crops on the early spring date, April 30, carries a 90% chance of a light frost and is therefore a gamble for Loveland gardeners. By contrast, the cautious spring date is May 22, when only a 10% chance of a light frost remains.

The 50% light-frost dates are May 10 in spring and October 1 in fall; May 10 marks a 50% chance of a frost later than this date, while October 1 marks a 50% chance of a frost earlier than this date. For a careful schedule, the fall cautious date is September 15, with just a 10% chance that a light frost has already arrived. The hard-frost 50% dates are May 2 and October 10, and a hard frost at 28 °F can damage plants that would survive a 32 °F light frost, making it the more critical temperature threshold.

How to read the probabilities

The dates are probabilities from 30 years of weather, not a forecast for this year.

  • Spring: "10% after May 22" means that in about one spring out of ten a frost still happens after that date. The 90% date is the earliest: a frost after it happens in most years.
  • Fall: "10% before September 15" means that in about one fall out of ten the first frost arrives before that date.
  • 50% is the typical date: half of the years are earlier, half are later.
  • A light frost (32°F) damages tender plants; a hard frost (28°F) also stops most hardy vegetables.

Nearby weather stations

Map of weather stations near Loveland, CONumbered nearest stations: 1 — Fort Collins, CO — 10 mi; 2 — Fort Collins 4 E, CO — 10 mi; 3 — near Greeley, CO — 20 mi; 4 — Boulder, CO — 32 mi; 5 — Brighton, CO — 36 mi.COWYNE25 mi · 40 km1. Fort Collins, CO — 10 mi12. Fort Collins 4 E, CO — 10 mi23. near Greeley, CO — 20 mi34. Boulder, CO — 32 mi45. Brighton, CO — 36 mi5
  1. Fort Collins, CO 10 mi (16 km)
  2. Fort Collins 4 E, CO 10 mi (16 km)
  3. near Greeley, CO 20 mi (33 km)
  4. Boulder, CO 32 mi (52 km)
  5. Brighton, CO 36 mi (59 km)

Sources

* Hardiness zone 5b: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 40.435, -105.085.