– Issued during the locally defined growing season when minimum sheltered temperatures are forecast to be near or slightly above freezing () over an extensive area on nights with good radiational cooling conditions (e.g., light winds and clear skies). Widespread frost can be expected. Frost Advisories are usually issued to highlight frost events occurring during the locally defined starting and ending periods of the growing season, and will be intermediately issued when appropriate until the end of the growing season based on criteria set by the Weather Forecast Office. Hard freeze warning (NPW) – Minimum shelter temperatures are forecast to be or below over a widespread area during the growing season. A hard freeze may occur with or without frost. Temperature criteria may vary slightly in some county warning areas. Hard freeze watch (NPW) – Conditions are favorable for widespread sub-freezing temperatures that would meet or exceed Hard Freeze Warning criteria within the next 12 to 48 hours during the locally defined growing season. Heat advisory (NPW) – High Heat Index (HI) values are forecast to meet or exceed locally defined warning criteria for one or two days. Specific criteria vary over different county warning areas, due to climate variability and the effect of excessive heat on the local population. Usually issued within 12 hours of the onset of conditional advisory criteria, typical HI values are maximum daytime temperatures above for up to three hours per day, with minimum nighttime temperatures falling within or above the range of (depending on county warning area criteria) for two consecutive days. Warning criteria may be lowered by the issuing WFO if the heat event occurs early in the season, during a multi-day heat wave or during a widespread power outage occurring during a heat event due to severe weather phenomena (such as high winds, severe thunderstorms, or a derecho). Windchill Wind chill warning (NPW) – Extreme wind chills, capable of causing life-threatening medical conditions (such as severe frostbite and hypothermia) or death associated with accelerated heat loss from exposed skin, are imminent or occurring. The apparent temperature and wind speed criteria vary significantly over different county warning areas based on climate variability. This product will be deprecated sometime in 2021, and be superseded by the Extreme Cold Warning product, which will include dual criteria for extreme wind chill and actual temperature values, and have its use expanded to WFOs elsewhere in the conterminious