Where Milpa works
Milpa works best in the United States, where frost dates come from NOAA weather stations in 50 states and 5 territories. 5 regions abroad get estimates from a weather model. Elsewhere, only daylength works for now.
Updated September 26, 2026.
In the United States
Frost dates come from 3,041 NOAA weather stations in 50 states and 5 territories, using the 1991 to 2020 climate normals.
- 33,046 of 33,144 ZIP codes (99.7%)
- Within 80 km of a station. Your frost dates are that station’s, and the app tells you how far away it is.
- 46 ZIP codes
- Between 80 and 160 km from the nearest station. The Plan shows that station’s dates as a rough sketch, graded A good hunch. The Calendar has no dated jobs for these places yet.
- 52 ZIP codes
- More than 160 km from any station, so no frost dates yet. All 52 are in remote Alaska, where the Arctic stations publish no spring frost date.
- Hardiness zone
- From the USDA 2023 Plant Hardiness Zone Map’s ZIP code list, which covers 40,502 ZIP codes across the lower 48 states, Alaska, Hawaii and Puerto Rico.
- Places where it rarely freezes
- At 82 stations a typical year has no freeze. There the app says frost is rare and the growing season runs all year. San Diego, Miami, Honolulu, San Juan and Guam are among them.
- ZIP code tools
- The frost odds and still-time tools on this site, and the app’s Answers page, take US ZIP codes only.
Outside the United States
You can pin a garden anywhere in the world. Daylength works everywhere, because it comes from latitude alone.
In 5 regions, frost dates and hardiness zones are estimated from the ERA5 weather model (1991 to 2020), in cells 2 degrees across. They are graded A good hunch. Within 80 km of a US weather station the station is used first, so cells that close to one are left out of the counts below.
- Europe
- 168 cells with frost dates, 256 with a hardiness zone
- Southern Canada
- 160 cells with frost dates, 131 with a hardiness zone
- Australia
- 8 cells with frost dates, 173 with a hardiness zone
- New Zealand
- 5 cells with frost dates, 7 with a hardiness zone
- Japan
- 44 cells with frost dates, 11 with a hardiness zone
A cell can land on high ground. Munich’s cell sits in the Alps, so its last frost falls in late June.
- Everywhere else
- Mexico, Central and South America, Africa and most of Asia have no frost dates and no hardiness zone yet, so plant teams there aren’t checked for winter survival or season length.
- The Calendar
- Outside the US the Calendar has no dated jobs yet, even where the Plan shows frost dates.
- Local services and units
- Soil test and extension office links point to US services. Measurements start in inches and °F, and you can switch both under Account.
The southern hemisphere
Southern gardens aren’t supported yet. The frost dates for Australia and New Zealand are worked out for southern seasons, but the app’s season wording and Calendar still follow the northern year. In spring, Home can tell a Melbourne gardener the season is over. Southern gardens get no grape pruning dates.
Languages
The app is in English and Spanish. The Spanish is machine-translated, and where the two differ, the English is the version that counts. The lines about your data, your safety and where a number comes from are first in line for a fluent reader.
On this site, the plant, plant team, rule, folklore and frost pages, the two ZIP code tools and these help pages have Spanish versions. The guides and explainers are English only for now.