Frost dates in Puerto Rico

Why frost dates vary across Puerto Rico

Every date on this site is calculated for one place at a time, from that place's own record, because frost is local: two towns an hour apart can differ by a fortnight in spring.

1 of the places here record no reliable air frost at all, so their rows read “none”. That does not mean nothing limits planting — heat, the wet season and day length take over as the constraint — and the crop pages say so where it applies.

How to read the table

Last frost is the median date of the final spring frost: in half of the years on record the last frost fell before it, in half after. First frost is the median date of the first autumn frost, and season is the number of frost-free days between them. All three are measured at the 0 °C air-temperature threshold.

A median is a planning date, not a guarantee. Plant tender crops on it and you accept roughly a one-in-two chance of a later frost in any given year. Each town page shows the cautious date — safe in nine years out of ten — alongside it, together with the earliest and latest frost the record holds. Read how the figures are calculated.