# What a Freeze Warning means, and how it differs from a Frost Advisory Published November 8, 2026, 9:16 AM ET By Ryan Hall, Y'all Written by our automated news desk from National Weather Service data. A Frost Advisory covers lows of 33°F to 36°F on calm, clear nights. A Freeze Watch is the early heads-up, and a Freeze Warning means the low is forecast at 32°F or colder. This explainer covers what a hard freeze is, why these alerts only run in the growing season, and how to protect plants and outdoor pipes. ## Key points - **Frost Advisory:** lows of 33°F to 36°F on a clear, light-wind night. Frost can form and hurt sensitive plants. - **Freeze Watch:** conditions are favorable for a freeze in roughly the next 12 to 48 hours. Nothing is certain yet. - **Freeze Warning:** the low is forecast at 32°F or colder. Crops and garden plants are at risk, and so are unprotected outdoor pipes. - **Hard freeze:** a deeper freeze, 28°F or lower for an extended time. It is announced inside a Freeze Warning, not as its own alert. - **Growing season:** all three alerts are only issued while the local growing season is underway. A Freeze Warning means the minimum shelter temperature is forecast to hit 32°F or colder during the growing season, which is cold enough to kill tender plants. A Frost Advisory is the milder step, for lows of 33°F to 36°F on calm, clear nights. A Freeze Watch is the early heads-up that a warning could be on the way. These are the National Weather Service's definitions. ## Frost Advisory A Frost Advisory is for nights when the official low is forecast to land between 33°F and 36°F and the setup favors frost. That setup is good radiational cooling, with light winds and clear skies. Frost is thin ice crystals on the ground and other surfaces. They form when the surface itself drops below 32°F. That is why frost can show up even when the thermometer reads in the mid 30s. The advisory is aimed at sensitive vegetation. ## Freeze Watch A Freeze Watch means conditions are favorable for a freeze that would meet Freeze Warning criteria in the next 12 to 48 hours. It is meant to flag a potential for significant, widespread freezing temperatures while you still have time to get ready. The National Weather Service issues a watch when there is a 50 percent or greater chance of the event meeting local criteria. A watch can be upgraded to a warning if warning criteria become likely. In the fall, Freeze Watches run until the end of the growing season. In the spring, they start up when the growing season begins. ## Freeze Warning A Freeze Warning is issued when the minimum shelter temperature is forecast at 32°F or less during the growing season. The shelter temperature is the official air temperature reading. Warnings go out when the chance of that happening is 80 percent or greater. A warning is about a freeze covering a large area for an extended period. That is cold enough to kill some types of commercial crops and residential plants. It applies whether or not frost actually forms. ## What a hard freeze is A hard freeze is when the air temperature reaches 28°F or lower for an extended period. That is cold enough to kill most types of vegetation. There is no separate hard freeze alert. When one is expected, it shows up in the details of a Freeze Warning, with wording like "Hard freeze with temperatures as low as 21 expected." A frost severe enough to end the growing season, or delay its start, is called a "killing frost." ## Why these alerts only run in the growing season All three alerts exist to protect growing things, so they are tied to the growing season. Each area defines its own, which means the start and end dates differ from place to place. The 32°F and 33°F to 36°F thresholds above come from the national instruction. The season that switches these alerts on and off is set locally. ## What to do - **Protect tender plants.** Take steps to shield them from the cold before the low arrives. A Frost Advisory is your cue for anything sensitive, and a Freeze Warning means the risk is higher. - **Protect outdoor water pipes.** To keep them from freezing and bursting, wrap them, drain them, or let them drip slowly. - **Handle sprinklers.** If you have an in-ground sprinkler system, drain it and cover the above-ground pipes. - **Use a watch as your window.** A Freeze Watch gives you advance notice to prepare in case a warning is issued. You can also sign up for [free Y'all Alerts](/alerts) to get these in time. For what is active right now, see our [live warnings](/warnings). More on: [Weather explainers](https://ryanhallyall.com/news/topic/weather-explainers) ## Sources - [NWS Instruction 10-515, "WFO Non-Precipitation Weather Products Specification" (May 16, 2025), Table 1 and the Freeze Warning example](https://www.weather.gov/media/directives/010_pdfs/pd01005015curr.pdf), NOAA National Weather Service, issued May 15, 2025, 8:00 PM ET - [NWS safety page "Freeze Watch vs Warning and Frost Advisory"](https://www.weather.gov/safety/cold-ww), NOAA National Weather Service - [NWS Glossary, "freeze", "hard freeze", "frost"](https://forecast.weather.gov/glossary.php?word=freeze), NOAA National Weather Service --- Canonical: https://ryanhallyall.com/news/what-a-freeze-warning-frost-advisory-and-hard-freeze-mean From Ryan Hall, Y'all (https://ryanhallyall.com). Always follow official warnings from the National Weather Service.