NOAA_Enso_fig1 Published September 12, 2009 at 798 × 527 in El Niño is expected to strengthen and last through the Northern Hemisphere winter 2009-2010 Next → Figure 1. Average weekly sea surface temperature (SST) anomalies (°C) centered on 2 September 2009. Anomalies are computed with respect to the 1971-2000 base period weekly means (Xue et al. 2003, J. Climate, 16, 1601-1612).