Frost
Ice crystals that form on surfaces when the temperature drops to 32°F (0°C) or below and moisture in the air freezes. Frost can damage crops and plants and makes surfaces slippery. A frost advisory warns of light frost; a freeze warning indicates sustained freezing temperatures.
More Winter Weather Terms
Black Ice
A thin, transparent layer of ice on road surfaces that is nearly invisible, making it extremely dangerous for drivers. Black ice forms when temperatures drop rapidly after rain or from refreezing meltwater, often at night or in shaded areas.
Lake Effect Snow
Intense, localized snowfall produced when cold air moves across relatively warm lake water, picking up moisture and heat. Lake effect snow can produce snowfall rates of 2-4 inches per hour and create dramatic differences in accumulation over short distances.
Alberta Clipper
A fast-moving low-pressure system that originates near Alberta, Canada, and tracks southeast across the northern United States. Clippers typically bring light snow (1-4 inches) followed by bitter cold and gusty winds.
Nor'easter
A storm along the East Coast with winds blowing from the northeast. Nor'easters can bring heavy snow, rain, and coastal flooding, especially from Virginia to New England. The most powerful nor'easters rival hurricanes in intensity.
Freezing Fog
Fog that forms when air temperature is below 32°F (0°C), depositing ice crystals on exposed surfaces. Freezing fog creates treacherous driving conditions and can coat everything with a layer of rime ice.
Ice Storm
A storm that produces significant ice accumulation from freezing rain, typically 0.25 inches or more. Ice storms can down trees and power lines, causing widespread outages lasting days to weeks. They are among the most damaging winter weather events.
Explore Other Terms
Tornado
A violently rotating column of air extending from a thunderstorm to the ground. Tornadoes can produce winds exceeding 300 mph and cause catastrophic damage along their path. They are rated on the Enhanced Fujita (EF) scale from EF0 to EF5.
Supercell
A severe thunderstorm characterized by a deep, persistently rotating updraft called a mesocyclone. Supercells are the most dangerous type of thunderstorm and can produce tornadoes, large hail, damaging winds, and flash flooding.
Freezing Rain
Rain that falls as liquid but freezes on contact with surfaces at or below 32°F (0°C), creating a coating of ice called glaze. Freezing rain is extremely dangerous as it can make roads impassable and cause widespread power outages from ice-coated power lines.
Sleet
Frozen raindrops that bounce when hitting the ground. Sleet forms when snowflakes partially melt falling through a warm layer, then refreeze in a cold layer near the surface. Unlike freezing rain, sleet is frozen before it hits the ground.
Barometric Pressure
The weight of the atmosphere pressing down on a given point, measured in inches of mercury (inHg) or millibars (mb). Rising pressure typically indicates improving weather, while falling pressure suggests approaching storms or precipitation.
Dew Point
The temperature at which air becomes saturated and water vapor begins to condense into liquid. A higher dew point indicates more moisture in the air. Dew points above 65°F feel humid, while above 70°F is considered oppressive.
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Learn Frost in Context
These explainers and product surfaces connect this definition to real-world forecasting and decision-making.
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Learn the difference between wind chill, heat index, and 'feels like' temperature. Understand how each is calculated and when weather apps use them.
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What Does 'Feels Like' Temperature Mean? Wind Chill and Heat Index Explained
Understand wind chill, heat index, and wet-bulb temperature, why weather apps can disagree, and how to use apparent temperature alongside local safety guidance.
Helpful Tools and Hubs
Use these pages to apply the concept, compare conditions, or follow related weather workflows.
Guide
Ice Storm vs Freezing Rain vs Sleet
The key differences between winter precipitation types, how each forms, and how to stay safe.
Use Case
Weather App for Gardeners
Track frost risk, rainfall, and growing conditions for planting, watering, and harvest decisions.
Tool
Wind Chill Calculator
Estimate cold-weather exposure risk from temperature and wind speed.
Seasonal Hub
Winter Weather Guide
Find practical explainers on snow, freezing rain, wind chill, and winter travel risk.
See Frost in Action
WeatherAI brings weather concepts to life with professional radar, real-time alerts, and AI-powered forecasts that explain what the weather means for you.