Because of this year’s warm weather throughout the winter months, the accumulated chill hours that we have seen this year are even lower than last year’s values, and is only about 50% of what we usually expect by this time of year. If we use previous years of weather data to project the range of possible seasonal accumulations, it seems likely that we will end up lower than last year’s values.
Below I have one example from Peach County in central Georgia, accessed from AgroClimate.org on their web page at http://agroclimate.org/tools/Chill-Hours-Calculator/. The gold line shows the average accumulation of chill hours, the green line is last year’s, and the red line is this season to date with a range of projected values based on past years of data. It is interesting to see that the low values are not the result of one warm month but that the deficit has been steadily accumulating throughout the season. Note that the entire envelope of future possibilities lies below last year’s curve. And in fact the first part of February is expected to be fairly warm, which means we will probably tend towards the lower side of the envelope.
This is not good news for fruit farmers, who need the chill hours to make sure their trees set plenty of fruit for this year’s harvest. Will it be enough? That may depend on the variety planted, but we will have to wait and see what the final answer is later in spring.