A moderate La Niña climate phase is expected through spring 2021. This indicates that slightly above average temperatures and slightly less rainfall than normal can be expected in Florida’s citrus belt. Multi-county citrus Extension agent Ajia Paolillo made that announcement during a virtual Dec. 22 OJ Break presented by the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS).
The fact that the winter weather pattern is expected to be warmer than usual doesn’t rule out the possibility of a citrus freeze. Paolillo said a freeze can occur any winter, regardless of the climate phase.
La Niña is one of three climate phases that are part of the El Niño Southern Oscillation (ENSO) climate pattern. Others are El Niño, during which colder and wetter conditions are expected in Florida, and neutral, when conditions are neither El Niño nor La Niña.
Paolillo noted that Florida’s most severe freezes have occurred in weak La Niña, weak El Niño or neutral ENSO phases. Severe freezes in January 1981 and December 1989 occurred during neutral phases; those in December 1983 and January 1985 occurred during weak La Niña phases. The 1980s are remembered in Florida’s citrus industry for those four severe freezes; that many citrus-damaging freezes have not occurred in any other decade.
The most damaging freezes for Florida citrus are advection and radiation freezes, Paolillo said. In advection freezes, cold fronts move arctic air through the region. Radiation freezes feature overnight clear skies and light to no winds with periods of calm. Cold pockets and cold locations will have lower temperatures during radiation freezes. Break freezes and unsettled freezes are the other types of freezes.
Paolillo said that during a radiation freeze, cold air drains down and pools in low areas. “Know the cold pockets in your grove,” she suggested.
Read more on freeze protection for Florida citrus.
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