Garden Clock’s stated climate baseline is NOAA NCEI’s 1991–2020 U.S. Climate Normals. Source attribution is important, but it does not by itself prove that every site result is complete or correctly mapped.
Climate records
NOAA’s U.S. Climate Normals explains the available station-based products and provides access to the original records. When evaluating a frost result, check its station, reference period, temperature threshold, and probability where available.
Planting guidance
Crop timing should be interpreted separately from historical climate data. Our explanatory guides link to sources such as Colorado State University Extension and University of Minnesota Extension. Local recommendations and seed-packet instructions may differ.
Coverage and missing results
The lookup may not return a supported location for every search. Do not infer a frost date from a blank result, substitute an invented date, or assume the nearest town represents identical conditions. Use an original source when a result is unavailable.
Limits
Historical normals are not live forecasts. Local terrain and growing conditions can differ from a station. NOAA and the named universities are sources, not sponsors or endorsers of Garden Clock.
Corrections
Report a questionable value with the location, page URL, and source comparison through Contact. Our Editorial Policy describes correction standards.
The plugin includes 1991–2020 estimates for three named stations: New York Central Park, Chicago O’Hare, and Columbus airport. These do not establish coverage for every U.S. town. Station distance from your garden is not calculated. Unsupported places can use the manual-date calendar.