Frost dates for 80498 — Silverthorne, CO
Last spring frostJun 6median date
First fall frostSep 14median date
Growing season100 daysfrost-free
Hardiness zone5aZone 5a
How Silverthorne compares
- In 8 years out of 10, the last spring frost in Silverthorne falls between May 24 and June 23, a 30-day window. The first fall frost falls between August 31 and September 26.
- The median last frost is 26 days later than the Colorado median of May 11.
- Its 100-day growing season is longer than 13% of the 374 Colorado places with a regular frost season (state median 146 days).
- The last frost is 34 days later than the zone 5a median of May 3. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 5a chart.
- The weather station records an average of 235 nights a year at or below 32°F.
- Compared with Boulder, CO, 84 km away, the last frost here is 31 days later than there and the growing season is 52 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | May 24 |
| 50% (median) | June 6 |
| 10% (safe for tender plants) | June 23 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | August 31 |
| 50% (median) | September 14 |
| 90% (late) | September 26 |
Frost here means 32°F (0°C). A median date means half of years have their last frost earlier and half later.
Planting calendar for Silverthorne, CO
Frost dates for 80498 — Silverthorne, CO — last frost Jun 6, first frost Sep 14, zone 5a. whenisthelastfrost.com
Crop
JFMAMJJASOND
Start indoors: Mar 14 to Mar 28Transplant outside: May 9 to May 23
Start indoors: Mar 28 to Apr 11Transplant outside: Jun 20 to Jul 4
Start indoors: Mar 28 to Apr 11Transplant outside: Jun 20 to Jul 4
Start indoors: Apr 11 to Apr 25Transplant outside: Jun 13 to Jun 27
Start indoors: Apr 11 to Apr 25Transplant outside: May 16 to May 30Sow outdoors: May 9 to Jun 13Plant for fall: Jul 20 to Aug 17
Start indoors: Apr 11 to Apr 25Transplant outside: May 9 to May 23Sow outdoors: May 9 to May 23Plant for fall: Jul 6 to Jul 27
Start indoors: Apr 11 to Apr 25Transplant outside: May 23 to Jun 6
Start indoors: Apr 11 to Apr 25Transplant outside: May 16 to May 30
Start indoors: Apr 11 to Apr 25Transplant outside: May 23 to Jun 6
Start indoors: Apr 25 to May 9Transplant outside: Jun 27 to Jul 11Sow outdoors: Jun 27 to Jul 11
Start indoors: Apr 25 to May 9Transplant outside: Jun 13 to Jun 27
Sow outdoors: Apr 25 to May 16Plant for fall: Jun 22 to Jul 13
Sow outdoors: Apr 25 to May 16Plant for fall: Jul 20 to Aug 10
Sow outdoors: May 2 to Jun 13Plant for fall: Aug 3 to Aug 24
Start indoors: May 9 to May 16Transplant outside: Jun 20 to Jun 27Sow outdoors: Jun 13 to Jun 27
Start indoors: May 9 to May 16Sow outdoors: Jun 13 to Jun 27
Start indoors: May 9 to May 16Sow outdoors: Jun 13 to Jun 27
Start indoors: May 9 to May 16Transplant outside: Jun 20 to Jul 4
Sow outdoors: May 16 to Jun 13
Sow outdoors: May 16 to Jun 13Plant for fall: Jul 6 to Jul 20
Sow outdoors: May 16 to Jun 6
Sow outdoors: May 23 to Jun 20Plant for fall: Jul 6 to Jul 20
Sow outdoors: May 23 to Jun 13Plant for fall: Jul 20 to Aug 10
Sow outdoors: Jun 13 to Jul 4
Sow outdoors: Jun 13 to Jun 27
Transplant outside: Jun 20 to Jul 11
Plant for fall: Aug 31 to Oct 5
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Silverthorne, CO
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Mar 14 – Mar 28 | May 9 – May 23 | — | — |
| Peppers | Mar 28 – Apr 11 | Jun 20 – Jul 4 | — | — |
| Eggplant | Mar 28 – Apr 11 | Jun 20 – Jul 4 | — | — |
| Tomatoes | Apr 11 – Apr 25 | Jun 13 – Jun 27 | — | — |
| Lettuce | Apr 11 – Apr 25 | May 16 – May 30 | May 9 – Jun 13 | Jul 20 – Aug 17 |
| Kale | Apr 11 – Apr 25 | May 9 – May 23 | May 9 – May 23 | Jul 6 – Jul 27 |
| Broccoli | Apr 11 – Apr 25 | May 23 – Jun 6 | — | — |
| Cabbage | Apr 11 – Apr 25 | May 16 – May 30 | — | — |
| Cauliflower | Apr 11 – Apr 25 | May 23 – Jun 6 | — | — |
| Okra | Apr 25 – May 9 | Jun 27 – Jul 11 | Jun 27 – Jul 11 | — |
| Basil | Apr 25 – May 9 | Jun 13 – Jun 27 | — | — |
| Peas | — | — | Apr 25 – May 16 | Jun 22 – Jul 13 |
| Spinach | — | — | Apr 25 – May 16 | Jul 20 – Aug 10 |
| Radishes | — | — | May 2 – Jun 13 | Aug 3 – Aug 24 |
| Cucumbers | May 9 – May 16 | Jun 20 – Jun 27 | Jun 13 – Jun 27 | — |
| Zucchini & Summer Squash | May 9 – May 16 | — | Jun 13 – Jun 27 | — |
| Winter Squash & Pumpkins Warning: Your frost-free season is about 100 days, which is tight for winter squash & pumpkins (100+ days). Choose early varieties and use transplants or row covers. | May 9 – May 16 | — | Jun 13 – Jun 27 | — |
| Melons & Watermelon | May 9 – May 16 | Jun 20 – Jul 4 | — | — |
| Carrots | — | — | May 16 – Jun 13 | — |
| Beets | — | — | May 16 – Jun 13 | Jul 6 – Jul 20 |
| Potatoes | — | — | May 16 – Jun 6 | — |
| Swiss Chard | — | — | May 23 – Jun 20 | Jul 6 – Jul 20 |
| Cilantro | — | — | May 23 – Jun 13 | Jul 20 – Aug 10 |
| Green Beans | — | — | Jun 13 – Jul 4 | — |
| Sweet Corn | — | — | Jun 13 – Jun 27 | — |
| Sweet Potatoes Warning: Your frost-free season is about 100 days, which is tight for sweet potatoes (100+ days). Choose early varieties and use transplants or row covers. | — | Jun 20 – Jul 11 | — | — |
| Garlic | — | — | — | Aug 31 – Oct 5 |
Dates come from the median frost dates and common extension-service timing. Adjust for your soil temperature, microclimate and the varieties you grow.
About these dates
Based on 1991–2020 NOAA climate normals for the Green Mt Dam, CO weather station, 16 km away (elevation 7,740 ft (2,359 m)).
ZIP codes in Silverthorne: 80497 80498
Frost dates near Silverthorne
- Vail Jun 21 · Sep 7
- Parshall Jun 12 · Sep 10
- Frisco frost any month
- Minturn Jun 21 · Sep 7
- Dillon frost any month
- Avon Jun 21 · Sep 7
- Red Cliff Jun 21 · Sep 7
- Kremmling Jun 14 · Sep 5
Frequently asked questions
When is the last frost in Silverthorne, CO?
The median last spring frost in Silverthorne, CO is June 6. There is still about a 10% chance of frost after June 23, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Silverthorne, CO?
The median first fall frost is September 14, with about a 10% chance of frost before August 31.
How long is the growing season in Silverthorne, CO?
About 100 days between the median last spring frost and first fall frost.
What planting zone is Silverthorne, CO?
Silverthorne, CO is in USDA hardiness zone 5a.