U.S. Frost Dates by Weather Station

NOAA station USC00297867 · New Mexico

Frost Dates for San Jon, NM

NOAA weather station San Jon (USC00297867), New Mexico · elevation 4230 ft (1289 m) · hardiness zone 7a*

  • Lower-risk planting dateafter May 3only 1 spring in 10 still has a frost later
  • Typical last frostApril 1850% chance of a frost after it
  • Typical first fall frostOctober 2450% chance of a frost before it
  • Frost-free season187 daystypical year, 32°F
  • Hardiness zone7acalculated*

The year at a glance

Frost season at San Jon, NMSpring: a frost after April 1 in 9 years out of 10, after April 18 in half of the years, after May 3 in 1 year out of 10. Fall: the first frost comes before October 11 in 1 year out of 10, before October 24 in half of the years, before November 4 in 9 years out of 10. Typical frost-free season: 187 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 18First frost ~Oct 24Frost season at San Jon, NMSpring: a frost after April 1 in 9 years out of 10, after April 18 in half of the years, after May 3 in 1 year out of 10. Fall: the first frost comes before October 11 in 1 year out of 10, before October 24 in half of the years, before November 4 in 9 years out of 10. Typical frost-free season: 187 days.JFMAMJJASONDLast frost ~Apr 18First frost ~Oct 24
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 29 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 3October 11
50% (typical)April 18October 24
90% (likely)April 1November 4
Frost-free season (32°F, 50% chance)
187 days
Hard frost (28°F), last in spring, 50% chance after
April 6
Hard frost (28°F), first in fall, 50% chance before
November 3

The last 15 years (2006–2020 normals)

Typical last frost April 18 (same as the 30-year normal), typical first fall frost October 23 (1 day earlier). Frost-free season 189 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 San Jon: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 3, 20% April 28, 30% April 24, 40% April 21, 50% April 18, 60% April 15, 70% April 11, 80% April 7, 90% April 1.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 3Apr 18Apr 1Fall at San Jon: chance of a frost before this dateFall, chance of a frost before the date: 10% October 11, 20% October 16, 30% October 19, 40% October 21, 50% October 24, 60% October 27, 70% October 29, 80% November 1, 90% November 4.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 11Oct 24Nov 4
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

The cautious fall date in San Jon for finishing the harvest is October 11, when there is only a 10% chance of a light frost having arrived. By contrast, November 4 carries a 90% chance, making a late tender-crop harvest a gamble.

The 50% dates give the midpoint of frost risk. April 18 is the spring median for light frosts, meaning there is a 50% chance of a frost later than this date. October 24 is the fall median, with a 50% chance of a frost earlier than this date.

The cautious spring date for setting out tender crops is May 3, which carries a 10% chance of a light frost later. A hard frost at 28°F, reaching 50% likelihood on April 6 in spring and November 3 in fall, can damage plants more severely than a light frost, 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 3" 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 October 11" 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 San Jon, NMNumbered nearest stations: 1 — Tucumcari, NM — 21 mi; 2 — Ragland, NM — 33 mi; 3 — Friona, TX — 47 mi; 4 — Melrose, NM — 50 mi; 5 — Conchas Dam, NM — 53 mi.NMTX25 mi · 40 km1. Tucumcari, NM — 21 mi12. Ragland, NM — 33 mi23. Friona, TX — 47 mi34. Melrose, NM — 50 mi45. Conchas Dam, NM — 53 mi5
  1. Tucumcari, NM 21 mi (34 km)
  2. Ragland, NM 33 mi (53 km)
  3. Friona, TX 47 mi (76 km)
  4. Melrose, NM 50 mi (80 km)
  5. Conchas Dam, NM 53 mi (85 km)

Sources

* Hardiness zone 7a: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 35.1086, -103.3283.