| definition |
- The freeze/frost probability levels represent the risk with regard to meeting or falling below a certain temperature threshold by a specific date, or within a specified number of days. For example, suppose a 90 percent probability level for the spring season is computed to be March 1 at the 32 degree threshold. This means that nine years out of ten a temperature as cold or colder than 32 degrees is expected to occur later than March 1 during the spring season. For the fall season, the probability level represents the chance of having a temperature as cold or colder earlier than the computed date. The freeze-free probability level indicates the chance of having a longer freeze-free period than the computed number of days. The methods used to compute the freeze probabilities come from two data distributions: a discrete freeze or no-freeze distribution, where a no-freeze annual season is one in which only one or no freeze occurs; and a continuous one of freeze dates for the years of freeze occurrence, where at least two distinct freeze dates occur in a year.
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