A frost-date table is a summary of the past. It tells you when freezes typically came in 1991-2020 at a particular station. It does not tell you when the next one will come.
Normals describe a climate, not a season
NOAA's U.S. Climate Normals are 30-year averages and probabilities. They are the standard reference for "what is typical here". Individual years swing widely around the typical: an early warm spell, a late cold snap or an unusual fall can move a freeze date by weeks. The 10% and 90% dates show how wide that spread has been, and even they are not limits. In a given year the actual last freeze can fall outside them.
A station is not your yard
The reading at a weather station is for the spot where the instrument stands. Slopes, valleys, buildings, pavement, nearby water and tree cover can change your overnight minimum by several degrees. Use the table for planning and your own records for fine-tuning.
The climate is changing
The 1991-2020 normals are the most recent official set, and they include the warmer recent decades, but they are still an average of the past. We do not adjust or project them.
How to use them well
- Use the historical dates to plan the season: decide when seeds should start and when beds should be ready.
- As the date approaches, watch the current weather forecast from your national or local weather service for overnight lows.
- Keep a few days of flexibility, and keep row cover or another way of protecting plants nearby if you plant near the early end.
- Write down what happens in your yard, then adjust next year.
Every Quietcog garden product states that its dates are historical 1991-2020 averages, not a forecast and not a guarantee, and that the planting windows are generic offsets and not agricultural advice. Follow your seed packet and your local extension office.
Want the dates for your own station? See the Garden Calendars workbook and regional packs, or the free sample PDF. Next guide: Using the US Frost Dates & Planting Calendar Workbook: a five-minute walkthrough.
Please note. Historical 1991-2020 averages from NOAA; actual frost dates vary year to year; not a forecast or a guarantee; not agricultural advice. Planting windows are generic offsets from historical dates; follow your seed packet, your local extension office and the current weather forecast. This product is AI-assisted, so errors are still possible; please report them to gb1@mail.grokbot.com.
Source: Palecki, M., Durre, I., Applequist, S., Arguez, A., Lawrimore, J. (2021). U.S. Climate Normals 2020: U.S. Annual/Seasonal Climate Normals (1991-2020), version 1.0.1. NOAA National Centers for Environmental Information. doi:10.25921/4ek7-fk11. Quietcog is independent and is not affiliated with, endorsed by or sponsored by NOAA or the National Weather Service. Quietcog processed the station files; any processing errors are ours.
Support: gb1@mail.grokbot.com.