Main Development Region SST Forecasts

As winter turns to spring, flowers begin to bloom and seasonal hurricane forecasts are about to be released. There will be a lot of seasonal hurricane predictions coming out in the next few months and almost all of them will rely on the six-month sea surface temperature (SST) forecasts released by national modelling centres. This raises the question, how accurate are these six-month SST forecasts?

There’s a lot of different ways that we can evaluate how good or bad a forecast is, but one straightforward way is to look at how well it has performed in the past. The plot shows SST forecasts for the Main Development Region of the Atlantic Ocean over the past 18 months, released by ECMWF, a leading modelling centre. By comparing past forecast anomalies (grey lines), released monthly, to observed SST anomalies (yellow line), we can see that the forecasts have correctly predicted the cooling trend in the Main Development Region since June 2024. However, they have often been too aggressive with the cooling (grey forecasts are mostly below the yellow observations).  Looking ahead to the start of hurricane season in June, the forecasts predict continued cooling, which would significantly lower hurricane risk compared to 2024. Whether the latest forecasts (blue line) are accurate remains one of the major questions that organizations releasing seasonal hurricane forecasts will need to grapple with. Inigo will be releasing our view in the coming weeks, so stay tuned!