The sea surface temperature anomaly (SSTA) is the difference between the observed SST and the climatological SST. These anomalies are calculated on a weekly basis.
Positive SSTAs are usually correlated with increased regions of convection (cloudiness and rainfall) while negative SSTAs are usually correlated to reduced convection.
SSTAs can be used as an indicator of the phase of global climate fluctuations, such as the El Nino/Southern Oscillation (ENSO).
The data displayed in this map is the weekly average, centred on the date shown.
12:38 EST Tropical Cyclone Jack has rapidly developed over the warm waters of the Indian Ocean in the past 24 hours, making it the 10th system to be named this season.