Frost dates for 91017 — Monrovia, CA
Last spring frostApr 28median date
First fall frostNov 15median date
Growing season201 daysfrost-free
Hardiness zone10aZone 10a
How Monrovia compares
- In 8 years out of 10, the last spring frost in Monrovia falls between March 31 and May 27, a 57-day window. The first fall frost falls between October 18 and December 9.
- The median last frost is 28 days later than the California median of Mar 31.
- Its 201-day growing season is longer than 34% of the 636 California places with a regular frost season (state median 235 days).
- The last frost is 57 days later than the zone 10a median of Mar 2. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 10a chart.
- The weather station records an average of 50 nights a year at or below 32°F.
- Nearby Arcadia, CA, 4 km away, gets only light, occasional frost, a reminder of how much elevation and distance from the coast matter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | March 31 |
| 50% (median) | April 28 |
| 10% (safe for tender plants) | May 27 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | October 18 |
| 50% (median) | November 15 |
| 90% (late) | December 9 |
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 Monrovia, CA
Frost dates for 91017 — Monrovia, CA — last frost Apr 28, first frost Nov 15, zone 10a. whenisthelastfrost.com
Crop
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Start indoors: Feb 3 to Feb 17Transplant outside: Mar 31 to Apr 14
Start indoors: Feb 17 to Mar 3Transplant outside: May 12 to May 26
Start indoors: Feb 17 to Mar 3Transplant outside: May 12 to May 26
Start indoors: Mar 3 to Mar 17Transplant outside: May 5 to May 19
Start indoors: Mar 3 to Mar 17Transplant outside: Apr 7 to Apr 21Sow outdoors: Mar 31 to May 5Plant for fall: Sep 20 to Oct 18
Start indoors: Mar 3 to Mar 17Transplant outside: Mar 31 to Apr 14Sow outdoors: Mar 31 to Apr 14Plant for fall: Sep 6 to Sep 27
Start indoors: Mar 3 to Mar 17Transplant outside: Apr 14 to Apr 28Plant for fall: Aug 9 to Aug 30
Start indoors: Mar 3 to Mar 17Transplant outside: Apr 7 to Apr 21Plant for fall: Aug 9 to Aug 30
Start indoors: Mar 3 to Mar 17Transplant outside: Apr 14 to Apr 28Plant for fall: Aug 9 to Aug 30
Start indoors: Mar 17 to Mar 31Transplant outside: May 19 to Jun 2Sow outdoors: May 19 to Jun 2
Start indoors: Mar 17 to Mar 31Transplant outside: May 5 to May 19
Sow outdoors: Mar 17 to Apr 7Plant for fall: Aug 23 to Sep 13
Sow outdoors: Mar 17 to Apr 7Plant for fall: Sep 20 to Oct 11
Sow outdoors: Mar 24 to May 5Plant for fall: Oct 4 to Oct 25
Start indoors: Mar 31 to Apr 7Transplant outside: May 12 to May 19Sow outdoors: May 5 to May 19Plant for fall: Aug 30 to Sep 13
Start indoors: Mar 31 to Apr 7Sow outdoors: May 5 to May 19Plant for fall: Sep 6 to Sep 20
Start indoors: Mar 31 to Apr 7Sow outdoors: May 5 to May 19
Start indoors: Mar 31 to Apr 7Transplant outside: May 12 to May 26
Sow outdoors: Apr 7 to May 5Plant for fall: Aug 23 to Sep 6
Sow outdoors: Apr 7 to May 5Plant for fall: Sep 6 to Sep 20
Sow outdoors: Apr 7 to Apr 28
Sow outdoors: Apr 14 to May 12Plant for fall: Sep 6 to Sep 20
Sow outdoors: Apr 14 to May 5Plant for fall: Sep 20 to Oct 11
Sow outdoors: May 5 to May 26Plant for fall: Aug 30 to Sep 13
Sow outdoors: May 5 to May 19
Transplant outside: May 12 to Jun 2
Plant for fall: Nov 1 to Dec 6
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Monrovia, CA
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 3 – Feb 17 | Mar 31 – Apr 14 | — | — |
| Peppers | Feb 17 – Mar 3 | May 12 – May 26 | — | — |
| Eggplant | Feb 17 – Mar 3 | May 12 – May 26 | — | — |
| Tomatoes | Mar 3 – Mar 17 | May 5 – May 19 | — | — |
| Lettuce | Mar 3 – Mar 17 | Apr 7 – Apr 21 | Mar 31 – May 5 | Sep 20 – Oct 18 |
| Kale | Mar 3 – Mar 17 | Mar 31 – Apr 14 | Mar 31 – Apr 14 | Sep 6 – Sep 27 |
| Broccoli | Mar 3 – Mar 17 | Apr 14 – Apr 28 | — | Aug 9 – Aug 30 |
| Cabbage | Mar 3 – Mar 17 | Apr 7 – Apr 21 | — | Aug 9 – Aug 30 |
| Cauliflower | Mar 3 – Mar 17 | Apr 14 – Apr 28 | — | Aug 9 – Aug 30 |
| Okra | Mar 17 – Mar 31 | May 19 – Jun 2 | May 19 – Jun 2 | — |
| Basil | Mar 17 – Mar 31 | May 5 – May 19 | — | — |
| Peas | — | — | Mar 17 – Apr 7 | Aug 23 – Sep 13 |
| Spinach | — | — | Mar 17 – Apr 7 | Sep 20 – Oct 11 |
| Radishes | — | — | Mar 24 – May 5 | Oct 4 – Oct 25 |
| Cucumbers | Mar 31 – Apr 7 | May 12 – May 19 | May 5 – May 19 | Aug 30 – Sep 13 |
| Zucchini & Summer Squash | Mar 31 – Apr 7 | — | May 5 – May 19 | Sep 6 – Sep 20 |
| Winter Squash & Pumpkins | Mar 31 – Apr 7 | — | May 5 – May 19 | — |
| Melons & Watermelon | Mar 31 – Apr 7 | May 12 – May 26 | — | — |
| Carrots | — | — | Apr 7 – May 5 | Aug 23 – Sep 6 |
| Beets | — | — | Apr 7 – May 5 | Sep 6 – Sep 20 |
| Potatoes | — | — | Apr 7 – Apr 28 | — |
| Swiss Chard | — | — | Apr 14 – May 12 | Sep 6 – Sep 20 |
| Cilantro | — | — | Apr 14 – May 5 | Sep 20 – Oct 11 |
| Green Beans | — | — | May 5 – May 26 | Aug 30 – Sep 13 |
| Sweet Corn | — | — | May 5 – May 19 | — |
| Sweet Potatoes | — | May 12 – Jun 2 | — | — |
| Garlic | — | — | — | Nov 1 – Dec 6 |
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 Mt Wilson Cbs, CA weather station, 11 km away (elevation 5,709 ft (1,740 m)).
ZIP codes in Monrovia: 91016 91017
Frost dates near Monrovia
- Duarte Apr 28 · Nov 15
- Arcadia Jan 4 · Jan 2
- Sierra Madre Apr 28 · Nov 15
- Baldwin Park Jan 4 · Jan 2
- Temple City Jan 4 · Jan 2
- El Monte Jan 4 · Jan 2
- Azusa Jan 8 · Dec 28
- San Gabriel Jan 4 · Jan 2
Frequently asked questions
When is the last frost in Monrovia, CA?
The median last spring frost in Monrovia, CA is April 28. There is still about a 10% chance of frost after May 27, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Monrovia, CA?
The median first fall frost is November 15, with about a 10% chance of frost before October 18.
How long is the growing season in Monrovia, CA?
About 201 days between the median last spring frost and first fall frost.
What planting zone is Monrovia, CA?
Monrovia, CA is in USDA hardiness zone 10a.