U.S. Frost Dates by Weather Station

NOAA station USC00481284 · Wyoming

Frost Dates for Burris, WY

NOAA weather station Burris (USC00481284), Wyoming · elevation 6125 ft (1867 m) · hardiness zone 4b*

  • Lower-risk planting dateafter June 19only 1 spring in 10 still has a frost later
  • Typical last frostJune 150% chance of a frost after it
  • Typical first fall frostSeptember 1450% chance of a frost before it
  • Frost-free season104 daystypical year, 32°F
  • Hardiness zone4bcalculated*

The year at a glance

Frost season at Burris, WYSpring: a frost after May 17 in 9 years out of 10, after June 1 in half of the years, after June 19 in 1 year out of 10. Fall: the first frost comes before September 1 in 1 year out of 10, before September 14 in half of the years, before September 27 in 9 years out of 10. Typical frost-free season: 104 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Jun 1First frost ~Sep 14Frost season at Burris, WYSpring: a frost after May 17 in 9 years out of 10, after June 1 in half of the years, after June 19 in 1 year out of 10. Fall: the first frost comes before September 1 in 1 year out of 10, before September 14 in half of the years, before September 27 in 9 years out of 10. Typical frost-free season: 104 days.JFMAMJJASONDLast frost ~Jun 1First frost ~Sep 14
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 26 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)June 19September 1
50% (typical)June 1September 14
90% (likely)May 17September 27
Frost-free season (32°F, 50% chance)
104 days
Hard frost (28°F), last in spring, 50% chance after
May 15
Hard frost (28°F), first in fall, 50% chance before
September 26

The last 15 years (2006–2020 normals)

Typical last frost May 30 (2 days earlier than the 30-year normal), typical first fall frost September 14. Frost-free season 106 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 Burris: chance of a frost after this dateSpring, chance of a frost after the date: 10% June 19, 20% June 14, 30% June 8, 40% June 4, 50% June 1, 60% May 30, 70% May 27, 80% May 22, 90% May 17.Spring: last frostChance of a frost after this date10%50%90%Jun 1Jul 1Jun 19Jun 1May 17Fall at Burris: chance of a frost before this dateFall, chance of a frost before the date: 10% September 1, 20% September 4, 30% September 8, 40% September 12, 50% September 14, 60% September 17, 70% September 20, 80% September 23, 90% September 27.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 1Sep 14Sep 27
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

September 1 is the cautious fall date for finishing the harvest of tender crops in Burris; only a 10% chance of a light frost has arrived earlier. The 50% date in fall is September 14, marking a 50% chance of a light frost earlier than this date, while the 90% date of September 27 signals a gamble for crops that stay out later.

The 50% date in spring is June 1, indicating a 50% chance of a light frost later than this date. For a cautious plan, the late spring date of June 19 carries a 10% chance of a frost later, whereas the early spring date of May 17 carries a 90% chance and is a gamble for tender crops.

The 50% hard-frost dates are May 15 and September 26; hard frost at 28°F can damage plant tissue that often survives a light frost at 32°F. The record spans 26 years with 104 days between the two 32°F 50% dates.

How to read the probabilities

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

  • Spring: "10% after June 19" 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 1" 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 Burris, WYNumbered nearest stations: 1 — near Lander, WY — 47 mi; 2 — Thermopolis, WY — 57 mi; 3 — Worland (USW00024062), WY — 78 mi; 4 — Cody, WY — 79 mi; 5 — Worland (USC00489770), WY — 79 mi.WY50 mi · 80 km1. near Lander, WY — 47 mi12. Thermopolis, WY — 57 mi23. Worland (USW00024062), WY — 78 mi34. Cody, WY — 79 mi45. Worland (USC00489770), WY — 79 mi5
  1. near Lander, WY 47 mi (76 km)
  2. Thermopolis, WY 57 mi (92 km)
  3. Worland (USW00024062), WY 78 mi (126 km)
  4. Cody, WY 79 mi (127 km)
  5. Worland (USC00489770), WY 79 mi (127 km)

Sources

* Hardiness zone 4b: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 43.3656, -109.2756.