Denver garden climate data
Weekly air and soil temperatures, the frost record, and heat counts for Denver from ERA5-Land model output (cell 39.70, -105.00; 35 seasons (1991–2025)). Elevation about 1640 m. Values are model output for a ~10 km grid cell, not a local weather station.
How these dates are judged
- Last frost
- The typical last spring date when frost is still expected.
- First frost
- The typical first fall date when frost returns.
- Frost-free days
- The approximate days between those two dates.
- Cool-season vegetables
- Crops that prefer cooler weather, such as lettuce, kale, peas, and radish.
- Warm-season vegetables
- Crops that need warm weather and cannot take frost, such as tomato, pepper, squash, and beans.
- Soil freeze
- The typical date when 0–7 cm soil first stays at or below 0 °C for three days — the autumn planting anchor for crops such as hardneck garlic.
Cool-season planting window
May 4 – Jun 21; Sep 7 – Oct 11 (84 days)
Warm-season planting window
Jun 8 – Sep 6 (91 days)
Usually too cold
- January 1 – May 3
- October 12 – December 31
Weekly temperatures and planting windows
- Possible min to max
- Average min to max
- Suitable
- Tolerable
- Too cold
- Too hot
Selected week · tap a week or use the arrows
Week 19 · May 4 – May 10
Average 4 to 19 °C · Possible −5 to 30 °C
Cool season: tolerable
Warm season: too cold
A week is suitable for a crop type when its average low and high sit inside that type's range and its possible readings stay within the frost and heat limits (cool: −2 °C to 27 °C, warm: 0 °C to 32 °C); crossing a limit makes it tolerable, and for warm crops any chance of frost makes it too cold.
Based on average frost and soil-freeze dates (35 seasons (1991–2025)).
- Cool
- Warm
- Frost
- Soil freeze
Colorado, United States · 39.7, -105 · 2026
Show all 53 weeks
Soil temperatures
Weekly 0–7 cm soil temperature for Denver. Crop timing uses soil limits at 4 °C40 °F4 °C (40 °F), 7 °C45 °F7 °C (45 °F), 10 °C50 °F10 °C (50 °F), 16 °C60 °F16 °C (60 °F), 18 °C65 °F18 °C (65 °F).
The ground usually freezes around Jan 1 (most winters).
| Week | Dates | Avg low | Avg high | Possible low | Possible high |
|---|---|---|---|---|---|
| 1 | Jan 1 – Jan 4 | −2 °C29 °F−2 °C (29 °F) | 0 °C32 °F0 °C (32 °F) | −8 °C17 °F−8 °C (17 °F) | 7 °C45 °F7 °C (45 °F) |
| 2 | Jan 5 – Jan 11 | −2 °C29 °F−2 °C (29 °F) | 0 °C32 °F0 °C (32 °F) | −11 °C12 °F−11 °C (12 °F) | 9 °C48 °F9 °C (48 °F) |
| 3 | Jan 12 – Jan 18 | −2 °C29 °F−2 °C (29 °F) | 0 °C32 °F0 °C (32 °F) | −10 °C13 °F−10 °C (13 °F) | 6 °C42 °F6 °C (42 °F) |
| 4 | Jan 19 – Jan 25 | −1 °C30 °F−1 °C (30 °F) | 0 °C33 °F0 °C (33 °F) | −7 °C20 °F−7 °C (20 °F) | 10 °C50 °F10 °C (50 °F) |
| 5 | Jan 26 – Feb 1 | −1 °C30 °F−1 °C (30 °F) | 1 °C33 °F1 °C (33 °F) | −8 °C17 °F−8 °C (17 °F) | 14 °C58 °F14 °C (58 °F) |
| 6 | Feb 2 – Feb 8 | −1 °C30 °F−1 °C (30 °F) | 1 °C34 °F1 °C (34 °F) | −10 °C15 °F−10 °C (15 °F) | 11 °C52 °F11 °C (52 °F) |
| 7 | Feb 9 – Feb 15 | −1 °C30 °F−1 °C (30 °F) | 1 °C34 °F1 °C (34 °F) | −9 °C15 °F−9 °C (15 °F) | 16 °C61 °F16 °C (61 °F) |
| 8 | Feb 16 – Feb 22 | −1 °C31 °F−1 °C (31 °F) | 2 °C36 °F2 °C (36 °F) | −8 °C18 °F−8 °C (18 °F) | 16 °C61 °F16 °C (61 °F) |
| 9 | Feb 23 – Mar 1 | −1 °C31 °F−1 °C (31 °F) | 3 °C38 °F3 °C (38 °F) | −7 °C20 °F−7 °C (20 °F) | 15 °C60 °F15 °C (60 °F) |
| 10 | Mar 2 – Mar 8 | 0 °C31 °F0 °C (31 °F) | 6 °C42 °F6 °C (42 °F) | −4 °C26 °F−4 °C (26 °F) | 18 °C65 °F18 °C (65 °F) |
| 11 | Mar 9 – Mar 15 | 0 °C32 °F0 °C (32 °F) | 9 °C47 °F9 °C (47 °F) | −7 °C19 °F−7 °C (19 °F) | 20 °C68 °F20 °C (68 °F) |
| 12 | Mar 16 – Mar 22 | 1 °C34 °F1 °C (34 °F) | 10 °C50 °F10 °C (50 °F) | −2 °C29 °F−2 °C (29 °F) | 24 °C75 °F24 °C (75 °F) |
| 13 | Mar 23 – Mar 29 | 2 °C35 °F2 °C (35 °F) | 11 °C52 °F11 °C (52 °F) | −7 °C19 °F−7 °C (19 °F) | 22 °C72 °F22 °C (72 °F) |
| 14 | Mar 30 – Apr 5 | 2 °C35 °F2 °C (35 °F) | 13 °C55 °F13 °C (55 °F) | −1 °C30 °F−1 °C (30 °F) | 26 °C79 °F26 °C (79 °F) |
| 15 | Apr 6 – Apr 12 | 3 °C37 °F3 °C (37 °F) | 15 °C58 °F15 °C (58 °F) | −2 °C29 °F−2 °C (29 °F) | 24 °C74 °F24 °C (74 °F) |
| 16 | Apr 13 – Apr 19 | 4 °C39 °F4 °C (39 °F) | 15 °C59 °F15 °C (59 °F) | −2 °C29 °F−2 °C (29 °F) | 25 °C77 °F25 °C (77 °F) |
| 17 | Apr 20 – Apr 26 | 5 °C40 °F5 °C (40 °F) | 16 °C61 °F16 °C (61 °F) | −1 °C30 °F−1 °C (30 °F) | 27 °C81 °F27 °C (81 °F) |
| 18 | Apr 27 – May 3 | 5 °C42 °F5 °C (42 °F) | 17 °C63 °F17 °C (63 °F) | 0 °C31 °F0 °C (31 °F) | 26 °C79 °F26 °C (79 °F) |
| 19 | May 4 – May 10 | 7 °C45 °F7 °C (45 °F) | 19 °C67 °F19 °C (67 °F) | 1 °C33 °F1 °C (33 °F) | 30 °C85 °F30 °C (85 °F) |
| 20 | May 11 – May 17 | 8 °C47 °F8 °C (47 °F) | 21 °C69 °F21 °C (69 °F) | 0 °C33 °F0 °C (33 °F) | 30 °C86 °F30 °C (86 °F) |
| 21 | May 18 – May 24 | 10 °C50 °F10 °C (50 °F) | 22 °C71 °F22 °C (71 °F) | 1 °C34 °F1 °C (34 °F) | 34 °C92 °F34 °C (92 °F) |
| 22 | May 25 – May 31 | 11 °C51 °F11 °C (51 °F) | 23 °C73 °F23 °C (73 °F) | 4 °C40 °F4 °C (40 °F) | 34 °C93 °F34 °C (93 °F) |
| 23 | Jun 1 – Jun 7 | 12 °C54 °F12 °C (54 °F) | 25 °C78 °F25 °C (78 °F) | 5 °C41 °F5 °C (41 °F) | 37 °C98 °F37 °C (98 °F) |
| 24 | Jun 8 – Jun 14 | 13 °C56 °F13 °C (56 °F) | 27 °C81 °F27 °C (81 °F) | 7 °C44 °F7 °C (44 °F) | 39 °C102 °F39 °C (102 °F) |
| 25 | Jun 15 – Jun 21 | 14 °C58 °F14 °C (58 °F) | 28 °C83 °F28 °C (83 °F) | 9 °C48 °F9 °C (48 °F) | 39 °C102 °F39 °C (102 °F) |
| 26 | Jun 22 – Jun 28 | 16 °C60 °F16 °C (60 °F) | 30 °C86 °F30 °C (86 °F) | 8 °C47 °F8 °C (47 °F) | 41 °C106 °F41 °C (106 °F) |
| 27 | Jun 29 – Jul 5 | 17 °C62 °F17 °C (62 °F) | 32 °C90 °F32 °C (90 °F) | 11 °C51 °F11 °C (51 °F) | 41 °C107 °F41 °C (107 °F) |
| 28 | Jul 6 – Jul 12 | 18 °C64 °F18 °C (64 °F) | 33 °C91 °F33 °C (91 °F) | 12 °C54 °F12 °C (54 °F) | 40 °C104 °F40 °C (104 °F) |
| 29 | Jul 13 – Jul 19 | 18 °C65 °F18 °C (65 °F) | 34 °C92 °F34 °C (92 °F) | 13 °C55 °F13 °C (55 °F) | 41 °C106 °F41 °C (106 °F) |
| 30 | Jul 20 – Jul 26 | 19 °C66 °F19 °C (66 °F) | 34 °C92 °F34 °C (92 °F) | 13 °C56 °F13 °C (56 °F) | 41 °C106 °F41 °C (106 °F) |
| 31 | Jul 27 – Aug 2 | 18 °C65 °F18 °C (65 °F) | 33 °C91 °F33 °C (91 °F) | 13 °C55 °F13 °C (55 °F) | 42 °C108 °F42 °C (108 °F) |
| 32 | Aug 3 – Aug 9 | 18 °C65 °F18 °C (65 °F) | 33 °C91 °F33 °C (91 °F) | 12 °C54 °F12 °C (54 °F) | 41 °C105 °F41 °C (105 °F) |
| 33 | Aug 10 – Aug 16 | 18 °C64 °F18 °C (64 °F) | 32 °C90 °F32 °C (90 °F) | 14 °C56 °F14 °C (56 °F) | 40 °C105 °F40 °C (105 °F) |
| 34 | Aug 17 – Aug 23 | 17 °C63 °F17 °C (63 °F) | 32 °C90 °F32 °C (90 °F) | 13 °C55 °F13 °C (55 °F) | 39 °C103 °F39 °C (103 °F) |
| 35 | Aug 24 – Aug 30 | 17 °C62 °F17 °C (62 °F) | 32 °C89 °F32 °C (89 °F) | 10 °C49 °F10 °C (49 °F) | 39 °C103 °F39 °C (103 °F) |
| 36 | Aug 31 – Sep 6 | 16 °C61 °F16 °C (61 °F) | 32 °C89 °F32 °C (89 °F) | 11 °C51 °F11 °C (51 °F) | 39 °C101 °F39 °C (101 °F) |
| 37 | Sep 7 – Sep 13 | 15 °C58 °F15 °C (58 °F) | 29 °C84 °F29 °C (84 °F) | 6 °C43 °F6 °C (43 °F) | 39 °C101 °F39 °C (101 °F) |
| 38 | Sep 14 – Sep 20 | 13 °C55 °F13 °C (55 °F) | 28 °C82 °F28 °C (82 °F) | 4 °C40 °F4 °C (40 °F) | 36 °C97 °F36 °C (97 °F) |
| 39 | Sep 21 – Sep 27 | 11 °C52 °F11 °C (52 °F) | 25 °C77 °F25 °C (77 °F) | 1 °C33 °F1 °C (33 °F) | 34 °C93 °F34 °C (93 °F) |
| 40 | Sep 28 – Oct 4 | 11 °C51 °F11 °C (51 °F) | 24 °C76 °F24 °C (76 °F) | 0 °C33 °F0 °C (33 °F) | 33 °C92 °F33 °C (92 °F) |
| 41 | Oct 5 – Oct 11 | 8 °C47 °F8 °C (47 °F) | 21 °C70 °F21 °C (70 °F) | 0 °C32 °F0 °C (32 °F) | 31 °C89 °F31 °C (89 °F) |
| 42 | Oct 12 – Oct 18 | 7 °C44 °F7 °C (44 °F) | 19 °C67 °F19 °C (67 °F) | −1 °C31 °F−1 °C (31 °F) | 29 °C85 °F29 °C (85 °F) |
| 43 | Oct 19 – Oct 25 | 5 °C42 °F5 °C (42 °F) | 18 °C64 °F18 °C (64 °F) | 0 °C31 °F0 °C (31 °F) | 29 °C83 °F29 °C (83 °F) |
| 44 | Oct 26 – Nov 1 | 4 °C39 °F4 °C (39 °F) | 13 °C56 °F13 °C (56 °F) | −2 °C28 °F−2 °C (28 °F) | 25 °C78 °F25 °C (78 °F) |
| 45 | Nov 2 – Nov 8 | 2 °C36 °F2 °C (36 °F) | 12 °C53 °F12 °C (53 °F) | −2 °C29 °F−2 °C (29 °F) | 22 °C71 °F22 °C (71 °F) |
| 46 | Nov 9 – Nov 15 | 1 °C34 °F1 °C (34 °F) | 10 °C49 °F10 °C (49 °F) | −9 °C17 °F−9 °C (17 °F) | 22 °C71 °F22 °C (71 °F) |
| 47 | Nov 16 – Nov 22 | 1 °C33 °F1 °C (33 °F) | 8 °C46 °F8 °C (46 °F) | −7 °C20 °F−7 °C (20 °F) | 22 °C71 °F22 °C (71 °F) |
| 48 | Nov 23 – Nov 29 | 0 °C33 °F0 °C (33 °F) | 5 °C40 °F5 °C (40 °F) | −3 °C26 °F−3 °C (26 °F) | 17 °C63 °F17 °C (63 °F) |
| 49 | Nov 30 – Dec 6 | 0 °C32 °F0 °C (32 °F) | 3 °C37 °F3 °C (37 °F) | −10 °C13 °F−10 °C (13 °F) | 19 °C66 °F19 °C (66 °F) |
| 50 | Dec 7 – Dec 13 | −1 °C30 °F−1 °C (30 °F) | 2 °C35 °F2 °C (35 °F) | −10 °C15 °F−10 °C (15 °F) | 11 °C52 °F11 °C (52 °F) |
| 51 | Dec 14 – Dec 20 | −1 °C30 °F−1 °C (30 °F) | 1 °C33 °F1 °C (33 °F) | −10 °C14 °F−10 °C (14 °F) | 12 °C53 °F12 °C (53 °F) |
| 52 | Dec 21 – Dec 27 | −1 °C30 °F−1 °C (30 °F) | 1 °C33 °F1 °C (33 °F) | −12 °C11 °F−12 °C (11 °F) | 15 °C59 °F15 °C (59 °F) |
| 53 | Dec 28 – Dec 31 | −1 °C30 °F−1 °C (30 °F) | 0 °C32 °F0 °C (32 °F) | −8 °C18 °F−8 °C (18 °F) | 8 °C46 °F8 °C (46 °F) |
Frost record by year
Last spring frost, first autumn frost, and frost-free days from ERA5-Land model output (1991–2025). Dates are not adjusted toward station values.
Last spring frost
- Median
- 8 in 10 years
Daily low ≤ 0 °C32 °F0 °C (32 °F), one tick per spring, 35 springs. Orange = average (median); shaded bar = dates of 8 in 10 springs.
First autumn frost
- Median
- 8 in 10 years
Daily low ≤ 0 °C32 °F0 °C (32 °F), one tick per autumn, 35 autumns. Orange = average (median); shaded bar = dates of 8 in 10 autumns.
| Year | Last spring frost | First autumn frost | Frost-free days |
|---|---|---|---|
| 1991 | May 6 | Oct 5 | 151 |
| 1992 | Apr 21 | Oct 8 | 169 |
| 1993 | May 10 | Sep 14 | 126 |
| 1994 | May 2 | Oct 25 | 175 |
| 1995 | May 18 | Sep 21 | 125 |
| 1996 | Apr 29 | Sep 27 | 150 |
| 1997 | May 3 | Oct 13 | 162 |
| 1998 | Apr 29 | Oct 18 | 171 |
| 1999 | May 12 | Sep 28 | 138 |
| 2000 | May 13 | Sep 24 | 133 |
| 2001 | May 21 | Oct 6 | 137 |
| 2002 | May 13 | Oct 15 | 154 |
| 2003 | May 12 | Oct 14 | 154 |
| 2004 | May 14 | Oct 30 | 168 |
| 2005 | May 3 | Oct 11 | 160 |
| 2006 | Apr 26 | Oct 17 | 173 |
| 2007 | Apr 26 | Oct 21 | 177 |
| 2008 | May 11 | Oct 14 | 155 |
| 2009 | Apr 21 | Oct 6 | 167 |
| 2010 | May 13 | Oct 27 | 166 |
| 2011 | May 5 | Oct 26 | 173 |
| 2012 | Apr 16 | Oct 7 | 173 |
| 2013 | May 5 | Oct 5 | 152 |
| 2014 | May 15 | Oct 3 | 140 |
| 2015 | May 11 | Oct 28 | 169 |
| 2016 | May 8 | Oct 20 | 164 |
| 2017 | May 20 | Oct 9 | 141 |
| 2018 | Apr 25 | Oct 10 | 167 |
| 2019 | May 24 | Oct 10 | 138 |
| 2020 | Apr 21 | Sep 8 | 139 |
| 2021 | May 13 | Oct 15 | 154 |
| 2022 | May 22 | Oct 27 | 157 |
| 2023 | Apr 24 | Oct 27 | 185 |
| 2024 | May 8 | Oct 31 | 175 |
| 2025 | Apr 22 | Oct 28 | 188 |
Heat
In a typical year, 29 of 53 weeks have a possible high above 27 °C81 °F27 °C (81 °F) (cool-crop limit), and 17 weeks go above 32 °C90 °F32 °C (90 °F) (warm-crop limit). The hottest week is week 27 (Jun 22 – Jun 28), with a possible high of 38 °C101 °F38 °C (101 °F).
Counts use weekly possible highs for Denver from the same ERA5-Land cell as the temperature chart.
Data and method
Source: ERA5-Land via the self-hosted Open-Meteo stack. Cool-season heat limit 27 °C; warm-season limit 32 °C. Soil markers at 4.4, 7.2, 10, 15.6 and 18.3 °C (0–7 cm).
Frost dates calculated by Plan & Plant from Weather data by Open-Meteo.com (CC BY 4.0).
Dates for Denver use ERA5-Land cell 39.70, -105.00 (1640 m). How we calculated this · Algorithm 2026-10-season-10.