U.S. Frost Dates by Weather Station

NOAA station USC00147093 · Kansas

Frost Dates for Saint Francis, KS

NOAA weather station Saint Francis (USC00147093), Kansas · elevation 3336 ft (1017 m) · hardiness zone 6a*

  • Lower-risk planting dateafter May 15only 1 spring in 10 still has a frost later
  • Typical last frostApril 3050% chance of a frost after it
  • Typical first fall frostOctober 1050% chance of a frost before it
  • Frost-free season160 daystypical year, 32°F
  • Hardiness zone6acalculated*

The year at a glance

Frost season at Saint Francis, KSSpring: a frost after April 18 in 9 years out of 10, after April 30 in half of the years, after May 15 in 1 year out of 10. Fall: the first frost comes before September 27 in 1 year out of 10, before October 10 in half of the years, before October 20 in 9 years out of 10. Typical frost-free season: 160 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 30First frost ~Oct 10Frost season at Saint Francis, KSSpring: a frost after April 18 in 9 years out of 10, after April 30 in half of the years, after May 15 in 1 year out of 10. Fall: the first frost comes before September 27 in 1 year out of 10, before October 10 in half of the years, before October 20 in 9 years out of 10. Typical frost-free season: 160 days.JFMAMJJASONDLast frost ~Apr 30First frost ~Oct 10
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 30 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 15September 27
50% (typical)April 30October 10
90% (likely)April 18October 20
Frost-free season (32°F, 50% chance)
160 days
Hard frost (28°F), last in spring, 50% chance after
April 20
Hard frost (28°F), first in fall, 50% chance before
October 18

The last 15 years (2006–2020 normals)

Typical last frost May 2 (2 days later than the 30-year normal), typical first fall frost October 12 (2 days later). Frost-free season 162 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 Saint Francis: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 15, 20% May 10, 30% May 6, 40% May 3, 50% April 30, 60% April 28, 70% April 25, 80% April 21, 90% April 18. Observed last spring frost in recent years: 2021 April 24, 2022 May 1, 2023 April 29, 2025 April 16.Spring: last frostChance of a frost after this date10%50%90%May 1May 15Apr 30Apr 182021: April 242022: May 12023: April 292025: April 16Fall at Saint Francis: chance of a frost before this dateFall, chance of a frost before the date: 10% September 27, 20% October 3, 30% October 6, 40% October 8, 50% October 10, 60% October 12, 70% October 15, 80% October 17, 90% October 20. Observed first fall frost in recent years: 2021 October 14, 2023 October 7, 2024 November 1, 2025 October 19.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 27Oct 10Oct 202021: October 142023: October 72024: November 12025: October 19
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
2021April 24October 14
2022May 1incomplete record
2023April 29October 7
2024incomplete recordNovember 1
2025April 16October 19
2026incomplete recordseason not over yet

What these dates mean

May 15 is the cautious spring light-frost date for Saint Francis, Kansas; with only a 10 % chance of a frost later than that day, gardeners can begin setting out tender crops with relatively low risk.

The 50 % light-frost dates are April 30 and October 10; April 30 marks a 50 % chance of a frost later than that date, and October 10 marks a 50 % chance of a frost earlier than that date, providing a midpoint of uncertainty. The median hard-frost dates are April 20 and October 18; a hard frost at 28 °F can damage tender plants more severely than a light frost at 32 °F, making it a more critical threshold.

September 27 is the cautious fall light-frost date, with a 10 % chance that a frost has arrived earlier; finishing harvesting tender crops after that date keeps risk low, while October 20 carries a 90 % chance of a frost earlier and is a gamble.

How to read the probabilities

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

  • Spring: "10% after May 15" 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 27" 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 Saint Francis, KSNumbered nearest stations: 1 — Bonny Dam 2 NE, CO — 18 mi; 2 — Benkelman, NE — 25 mi; 3 — Goodland, KS — 28 mi; 4 — Wray, CO — 30 mi; 5 — Brewster, KS — 34 mi.COKSNE25 mi · 40 km1. Bonny Dam 2 NE, CO — 18 mi12. Benkelman, NE — 25 mi23. Goodland, KS — 28 mi34. Wray, CO — 30 mi45. Brewster, KS — 34 mi5
  1. Bonny Dam 2 NE, CO 18 mi (29 km)
  2. Benkelman, NE 25 mi (40 km)
  3. Goodland, KS 28 mi (45 km)
  4. Wray, CO 30 mi (49 km)
  5. Brewster, KS 34 mi (54 km)

Sources

* Hardiness zone 6a: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 39.7675, -101.8067.