U.S. Frost Dates by Weather Station

NOAA station USC00054172 · Colorado

Frost Dates for Hugo, CO

NOAA weather station Hugo 1 NW (USC00054172), Colorado · elevation 5025 ft (1532 m) · hardiness zone 5b*

  • Lower-risk planting dateafter May 25only 1 spring in 10 still has a frost later
  • Typical last frostMay 1050% chance of a frost after it
  • Typical first fall frostOctober 250% chance of a frost before it
  • Frost-free season143 daystypical year, 32°F
  • Hardiness zone5bcalculated*

The year at a glance

Frost season at Hugo, COSpring: a frost after April 30 in 9 years out of 10, after May 10 in half of the years, after May 25 in 1 year out of 10. Fall: the first frost comes before September 21 in 1 year out of 10, before October 2 in half of the years, before October 13 in 9 years out of 10. Typical frost-free season: 143 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 10First frost ~Oct 2Frost season at Hugo, COSpring: a frost after April 30 in 9 years out of 10, after May 10 in half of the years, after May 25 in 1 year out of 10. Fall: the first frost comes before September 21 in 1 year out of 10, before October 2 in half of the years, before October 13 in 9 years out of 10. Typical frost-free season: 143 days.JFMAMJJASONDLast frost ~May 10First frost ~Oct 2
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 28 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 25September 21
50% (typical)May 10October 2
90% (likely)April 30October 13
Frost-free season (32°F, 50% chance)
143 days
Hard frost (28°F), last in spring, 50% chance after
May 1
Hard frost (28°F), first in fall, 50% chance before
October 10

The last 15 years (2006–2020 normals)

Typical last frost May 13 (3 days later than the 30-year normal), typical first fall frost October 6 (4 days later). Frost-free season 146 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 Hugo: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 25, 20% May 19, 30% May 15, 40% May 13, 50% May 10, 60% May 8, 70% May 6, 80% May 3, 90% April 30.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 25May 10Apr 30Fall at Hugo: chance of a frost before this dateFall, chance of a frost before the date: 10% September 21, 20% September 25, 30% September 28, 40% September 30, 50% October 2, 60% October 4, 70% October 6, 80% October 9, 90% October 13.Fall: first frostChance of a frost before this date10%50%90%Oct 1Sep 21Oct 2Oct 13
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.

What these dates mean

Setting out tender crops on the early spring date, April 30, carries a 90% chance of a frost later, making it a gamble for Hugo gardeners. The cautious date to begin tender crops is May 25, when only a 10% chance of a later frost remains. In fall, the cautious date to finish harvesting tender crops is September 21, with a 10% chance that frost has already arrived, while waiting until October 13 raises the risk to 90%.

The 50% spring date, May 10, means a gardener faces an even chance of a light frost occurring after that day, and the 50% fall date, October 2, represents an even chance of a light frost occurring before that day.

The hard-frost median dates are May 1 and October 10; a hard frost at 28 °F can damage plants that survive a light frost at 32 °F, so it is a more critical 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 25" 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 21" 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 Hugo, CONumbered nearest stations: 1 — near Limon, CO — 13 mi; 2 — Byers, CO — 53 mi; 3 — Joes, CO — 56 mi; 4 — Eads, CO — 60 mi; 5 — Tacony, CO — 63 mi.KS25 mi · 40 km1. near Limon, CO — 13 mi12. Byers, CO — 53 mi23. Joes, CO — 56 mi34. Eads, CO — 60 mi45. Tacony, CO — 63 mi5
  1. near Limon, CO 13 mi (20 km)
  2. Byers, CO 53 mi (86 km)
  3. Joes, CO 56 mi (90 km)
  4. Eads, CO 60 mi (97 km)
  5. Tacony, CO 63 mi (102 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: 39.1439, -103.4897.