Grand Junction, Colorado Frost Dates, Growing Season & Hardiness Zone
Frost odds and planting zone for Grand Junction for the 2027 season, based on 1991–2020 normals.
Last frost date
Apr 28
typical (50% chance of a later 32°F night)
Safer date: May 14 (10% risk)
earlyApr 28
typicalMay 14
safer
First fall frost
Oct 16
typical (50% chance it has happened by then)
Early-risk date: Oct 3 (10%)
Growing season
171 days
typical frost-free (32°F) season
Short year: 152 days (1 year in 10 is shorter)
USDA hardiness zone
6b–7a
2023 map: -5 to 5°F average coldest night
2012 map: 7a (most of the city)
Where you live in the metro matters. The typical last frost ranges from Apr 17 at Palisade to Apr 28 at Grand Junction Walker Field.
Half of years have their last 32°F night by Apr 28. In 1 year out of 10, a freeze still comes after May 14.
Based on NOAA station Grand Junction Walker Field (USW00023066), 3.5 mi NNE, elevation 4,858 ft (+210 ft vs. city center). Confidence: High.
When is the last frost in Grand Junction?
Expect the last 32°F night by Apr 28 in a typical year; 1 year in 10 still freezes after May 14. Cold 36°F nights (frost possible on plants) typically last longer, until around May 8. Hard freezes (28°F) typically end sooner, around Apr 13.
In Grand Junction, late frosts can come well after the typical date. The safer 1-in-10 date (May 14) is 16 days after the typical date (Apr 28). Tender plants set out early will need cover on cold nights.
Cool nights hang on after the last freeze: the typical last 36°F night (frost possible on plants in low spots) is around May 8, 10 days later than the typical last 32°F night. Frost can form on leaves on clear, calm nights even with the thermometer above freezing.
Our station has the latest typical last frost of the 4 eligible stations near Grand Junction. For most of the area, these dates are on the cautious side.
| Threshold | 10% (safer) | 30% | 50% (typical) | 90% (early) |
|---|---|---|---|---|
| 36°F (frost possible on plants) | May 25 | May 15 | May 8 | Apr 25 |
| 32°F freeze | May 14 | May 3 | Apr 28 | Apr 11 |
| 28°F hard freeze | May 2 | Apr 21 | Apr 13 | Mar 24 |
All probabilities (10–90%)
| Threshold | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F (frost possible on plants) | May 25 | May 19 | May 15 | May 11 | May 8 | May 5 | May 2 | Apr 30 | Apr 25 |
| 32°F freeze | May 14 | May 7 | May 3 | May 1 | Apr 28 | Apr 25 | Apr 21 | Apr 16 | Apr 11 |
| 28°F hard freeze | May 2 | Apr 26 | Apr 21 | Apr 17 | Apr 13 | Apr 9 | Apr 6 | Apr 2 | Mar 24 |
Is it safe to plant after Mother's Day in Grand Junction?
Many Grand Junction-area gardeners wait for Mother's Day to plant (CSU PlantTalk). In 2027, it falls on May 9. As of that date, the chance of another 32°F night is between 10% and 20%, and the chance of another 36°F night (frost possible on plants) is between 40% and 50% (NOAA 1991–2020, Grand Junction Walker Field).
Is it too early to plant in Grand Junction?
Before Apr 28 the odds of another 32°F night are better than even; after May 14 they are about 1 in 10 or less.
Today's risk is computed in your browser from the same NOAA probability table, shown as the range between the two nearest NOAA probability levels.
When is the first frost in Grand Junction?
The typical first fall freeze (32°F) comes by Oct 16, but 1 year in 10 it shows up as early as Oct 3. Cold 36°F nights (frost possible on plants) typically start around Oct 6, and the first hard freeze (28°F) typically comes around Oct 27.
For fall crops, count back from Oct 16, or from Oct 3 to be safe. Our planting calendar does the math for each crop.
| Threshold | 10% (early) | 30% | 50% (typical) | 90% (late) |
|---|---|---|---|---|
| 36°F (frost possible on plants) | Sep 24 | Oct 1 | Oct 6 | Oct 19 |
| 32°F freeze | Oct 3 | Oct 10 | Oct 16 | Oct 29 |
| 28°F hard freeze | Oct 12 | Oct 21 | Oct 27 | Nov 10 |
All probabilities (10–90%)
| Threshold | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F (frost possible on plants) | Sep 24 | Sep 29 | Oct 1 | Oct 4 | Oct 6 | Oct 9 | Oct 12 | Oct 15 | Oct 19 |
| 32°F freeze | Oct 3 | Oct 7 | Oct 10 | Oct 14 | Oct 16 | Oct 19 | Oct 22 | Oct 25 | Oct 29 |
| 28°F hard freeze | Oct 12 | Oct 17 | Oct 21 | Oct 24 | Oct 27 | Oct 30 | Nov 2 | Nov 6 | Nov 10 |
How long is Grand Junction's growing season?
Grand Junction's frost-free season (32°F) typically runs 171 days. In about 1 year out of 10, it's shorter than 152 days.
A season this long fits most warm-season vegetables planted on time. Long-season crops do best when started from transplants.
The station averages 3,634 growing degree days (base 50°F) a year. That number measures how much heat crops have to grow on.
| Threshold | 10% (long year) | 50% (typical) | 90% (short year) |
|---|---|---|---|
| 36°F (frost possible on plants) | 169 days | 152 days | 131 days |
| 32°F freeze | 190 days | 171 days | 152 days |
| 28°F hard freeze | 219 days | 196 days | 170 days |
How does Grand Junction's season compare?
Of the 20 Colorado cities with frost dates on this site, Grand Junction has a typical frost-free season of 171 days, which is the longest.
Compared with the 56 U.S. cities with frost dates on this site, this typical frost-free season is longer than in 19 and shorter than in 36.
Growing degree days (base 50°F)
Annual normal: 3,634 GDD (NOAA flag S, 28 years). Running total by the end of each month (sum of NOAA daily GDD normals, so the year-end total can differ slightly from the annual normal):
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 0 | 1 | 33 | 162 | 541 | 1,231 | 2,136 | 2,950 | 3,465 | 3,624 | 3,633 | 3,633 |
What growing zone is Grand Junction? (USDA 2023)
The 2023 USDA map puts Grand Junction in zone 6b–7a (-5 to 5°F average coldest winter night). On the 2012 map, most of the city was 7a. Comparing ZIPs listed in both tables, 1 of 6 moved up half a zone.
| ZIP | 2023 | 2012 | Change | Share of ZIP in Grand Junction |
|---|---|---|---|---|
| 81501 mostly in city | 7a | 7a | unchanged | 89% |
| 81503 | 7a | 7a | unchanged | 14% |
| 81504 | 7a | 7a | unchanged | 18% |
| 81505 | 6b | 6b | unchanged | 12% |
| 81506 | 7a | 7a | unchanged | 37% |
| 81507 | 7a | 6b | +1 half zone (warmer) | 5% |
Other ZIPs touching Grand Junction and PO-box ZIPs
ZIPs outside the 815 prefix that overlap the city boundary:
- none
PO-box and single-address 815xx ZIPs have no Census area, so we cannot tell which city they serve: 81502 (7a/7a), 81520 (7a/7a), 81521 (7a/6b), 81522 (6b/6b), 81523 (6b/6b), 81524 (6b/6b), 81525 (7a/6b), 81526 (7a/7a), 81527 (6a/6b) (2023/2012).
Zones: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed 2026-10-08. Shown as published in the ZIP tables; this page does not show a zone map. Not the official USDA Plant Hardiness Zone Map (official map: planthardiness.ars.usda.gov).
Does the new zone change Grand Junction's frost dates?
No. A hardiness zone reflects only the average coldest winter temperature, not the timing of spring or fall frost. Grand Junction's frost dates come from NOAA's 1991–2020 frost probabilities, and the 2023 zone map didn't change them. Pick perennials that survive winter by zone; time your planting by frost dates.
Why do Grand Junction frost dates differ between websites?
You may see May 3 given as Grand Junction's last frost date. That's the 30%-risk date, meaning about 3 years in 10 still have a 32°F night after it. Our headline date is Apr 28, the 50% (median) date.
The 'safer' date, May 14, is the 10%-risk date. A 32°F night after it happens in only about 1 year in 10.
May 8 is the typical (50%) date for a 36°F night (frost possible on plants), not a 32°F freeze. Any site that draws the line at 36°F will show later dates.
Sites also pick different weather stations. Within 25 miles of the city center, the 4 stations that meet our quality rules put the typical (50%) last 32°F frost anywhere from Apr 17 to Apr 28 (table below).
| Date | What it is (NOAA 1991–2020) |
|---|---|
| May 3 | 32°F last frost, 30% risk (a 'balanced' date) |
| May 8 | 36°F last cold night, 50% (frost possible on plants) |
| May 14 | 32°F last frost, 10% risk (the 'safer' date) |
| Apr 13 | 28°F last hard freeze, 50% |
| Apr 23 | 32°F last frost, 50%, at Grand Junction 6 ESE (nearest station with NOAA flag S) |
| Station | Distance | Elevation | Typical last frost |
|---|---|---|---|
| Palisade | 11.8 mi E | 4,751 ft | Apr 17 |
| Grand Junction 6 ESE | 6.3 mi ESE | 4,760 ft | Apr 23 |
| Fruita | 9.4 mi WNW | 4,498 ft | Apr 27 |
| Grand Junction Walker Field used here | 3.5 mi NNE | 4,858 ft | Apr 28 |
Which weather station is this based on?
- Station
- Grand Junction Walker Field (NOAA USW00023066, WBAN/ASOS-AWOS)
- Distance
- 3.5 mi NNE of the city center
- Elevation
- 4,858 ft; city center 4,648 ft (USGS), difference +210 ft
- Record
- NOAA completeness flag S, 29 of 30 years (1991–2020)
- Confidence
- High (rule)
Confidence: High. The station is 3.5 miles from the city center, only 210 ft different in elevation, and its frost statistics meet our completeness rule (NOAA flag S, 29 of 30 years).
| Station | ID | Distance | Elev. (Δ) | Last frost 50% | First frost 50% | Season 50% | NOAA flag / years |
|---|---|---|---|---|---|---|---|
| Grand Junction Walker Field | USW00023066 | 3.5 mi NNE | 4,858 ft (+210) | Apr 28 | Oct 16 | 171 d | S / 29 |
| Grand Junction 6 ESE | USC00053489 | 6.3 mi ESE | 4,760 ft (+112) | Apr 23 | Oct 20 | 179 d | S / 30 |
| Fruita | USC00053146 | 9.4 mi WNW | 4,498 ft (-150) | Apr 27 | Oct 11 | 164 d | R / 13 |
| Palisade | USC00056266 | 11.8 mi E | 4,751 ft (+103) | Apr 17 | Oct 26 | 190 d | S / 29 |
Other stations within 25 mi (not used)
- Grand Junction (USC00053486), 3.1 mi NE, 4,826 ft: typical last frost Apr 14. Not used: frost normals incomplete or flagged (needs all 81 values with S/R flags, or values missing only because NOAA's probability of occurrence is below 10%).
- Colorado National Monument (USC00051772), 9.0 mi W, 5,781 ft: typical last frost Apr 26. Not used: |elev diff| 1133 ft > 500 ft.
8 other NOAA normals stations within 40 km (mostly rain gauges) have no frost statistics.
Grand Junction planting dates at a glance
Balanced dates use the 30%-risk last-frost date as the anchor. The Grand Junction planting calendar has typical and safe dates, fall planting and a month-by-month list for 27 vegetables.
| Crop | Start indoors | Plant outdoors (balanced) | Fall |
|---|---|---|---|
| Tomatoes | Apr 13–27 | Jun 1 | – |
| Peppers | Mar 22 – Apr 5 | May 17 | – |
| Potatoes | – | Apr 19 – May 3 | – |
| Onions (dry, from sets) | – | Apr 5–19 | – |
| Peas | – | Apr 5–19 | sow by Jul 29 |
| Lettuce (leaf) | – | Apr 5–19 | sow by Aug 3 |
| Carrots | – | Apr 19 – May 3 | sow by Jul 24 |
| Beans (snap) | – | May 3 | sow by Jul 20 |
| Summer squash | – | May 3 | sow by Jul 30 |
| Broccoli | Feb 15 – Mar 1 | Apr 5–19 | transplant by Jul 29 |
| Cabbage | Feb 15 – Mar 1 | Apr 5–19 | transplant by Jul 9 |
| Cauliflower | Mar 1–15 | Apr 19 – May 3 | – |
| Kohlrabi | – | Apr 5–19 | sow by Aug 13 |
| Green onions | – | Apr 5–19 | sow by Aug 3 |
| Radishes | – | Apr 5–19 | sow by Sep 2 |
| Spinach | – | Apr 5–19 | sow by Aug 23 |
| Turnips | – | Apr 5–19 | sow by Aug 13 |
| Beets | – | Apr 19 – May 3 | sow by Aug 3 |
| Swiss chard | – | Apr 19 – May 3 | sow by Aug 3 |
| Parsnips | – | Apr 19 – May 3 | – |
| Sweet corn | – | May 3 | – |
| Cucumbers | – | May 3 | sow by Jul 25 |
| Eggplant | Mar 15 – Apr 5 | May 17 | – |
| Cantaloupe | – | May 17 | – |
| Watermelon | – | May 17 | – |
| Winter squash | – | May 17 | – |
| Garlic | – | – | plant Oct 1–14 |
When to plant tomatoes in Grand Junction · Fall planting dates for Grand Junction
Frost dates near Grand Junction
| City | Distance | Last frost | First frost | Season | Zone 2023 |
|---|---|---|---|---|---|
| Boulder frost dates | 188 mi | May 6 | Oct 5 | 151 days | 6a |
| Lakewood frost dates | 189 mi | May 3 | Oct 7 | 155 days | 6a |
| Arvada frost dates | 189 mi | May 5 | Oct 5 | 151 days | 6a |
| Littleton frost dates | 193 mi | May 2 | Oct 11 | 160 days | 5b–6a |
| Denver frost dates | 196 mi | Apr 30 | Oct 12 | 165 days | 6a |
| Longmont frost dates | 199 mi | May 7 | Oct 5 | 151 days | 5b–6a |
Frequently asked questions
What is the average last frost date in Grand Junction?
Apr 28 is the median (50%) date for Grand Junction's last 32°F night, from NOAA 1991–2020 normals at Grand Junction Walker Field. To play it safe, use May 14: only about 1 year in 10 has a freeze after it.
When is the first frost in Grand Junction?
The first 32°F night typically arrives by Oct 16. About 1 year in 10, it comes as early as Oct 3. A 36°F night (frost possible on plants) typically shows up around Oct 6.
What growing zone is Grand Junction, Colorado?
Grand Junction is in USDA hardiness zone 6b–7a on the 2023 map. Most of the city was already 7a on the 2012 map, though 1 of 6 city ZIPs changed zone.
Is it too early to plant in Grand Junction?
If it's before Apr 28, it's too early for frost-tender plants: another 32°F night is more likely than not. From Apr 28 to May 14, the risk falls from 50% to 10%. Cool-season crops such as peas and lettuce can be planted weeks earlier (see the planting calendar).
What temperature is a killing frost?
It depends on the crop. Tender plants such as tomatoes are killed by a light frost, which CSU Extension describes as 28–32°F; below 28°F is a heavy frost. We show NOAA odds for 36°F (frost possible on plants), 32°F (freeze, our headline) and 28°F (hard freeze).
Is first frost the same as first freeze?
Not exactly. A freeze is about the air reaching 32°F. Frost is ice on surfaces, which can form on calm, clear nights while the air is still a few degrees above freezing. So in Grand Junction, the first 36°F night (frost possible on plants) typically comes around Oct 6, ahead of the first 32°F night (Oct 16).
Download & sources
- Add Grand Junction frost & planting dates to your calendar (.ics, 2027)
- Printable planting calendar (PDF)
- How these numbers are calculated
Data: NOAA NCEI U.S. Climate Normals 1991–2020 (annual/seasonal and daily normals, station USW00023066); USDA Plant Hardiness Zone ZIP tables 2023 and 2012 by the PRISM Group, Oregon State University; Census 2020 ZIP/place relationship file; USGS elevation. Long-term odds, not a forecast. Figures and sentences are generated from these data by fixed rules; see the methodology. Last updated 2026-10-08.