The subsurface equatorial upper ocean heat profile foreshadows phase change of various modes of climate variability. In the Indian Ocean, the eastern portion of the equatorial region has warmed significantly (Fig. 1). Implied is evolution of a potentially strong negative phase of the Indian Ocean dipole (-IOD). The daily IOD index is robust -1.04. The -IOD regime has arrived. In the equatorial Pacific, the eastern portion has cooled significantly. Implied is an approaching La Nina episode.

The Indian Ocean Dipole has shifted to negative phase and a borderline La Nina is developing. The last time -IOD and La Nina were present during SEP/OCT was in 2022 when buckets of rain fell on the East/Southeast! Be aware of potential over-achieving rains in the East for spring 2025! The AI Graph Cast week 2-4 outlook reveals the upcoming wet pattern for East Australia.

The North Atlantic basin SSTA is +0.28C which is quite cool compared to other years this decade. The 1-year change is -0.53C which is very impressive. However, there are basins which are very warm and capable of contributing to over-achieving tropical cyclones and their intensity. The Gulf of Mexico is near record warm (+0.90C) which is steady during the past 2 weeks. The Caribbean Sea is also very warm and unchanged during the past 2 weeks.

The official U.S. population weight CDD for August 2025 from NOAA will be published in a few days. Climate Impact Company (CIC) projects 272 CDD for August which is cooler than the 30-year normal (290 CDD) and much cooler than the 10-year normal (332 CDD). The NOAA assessment is (more) likely cooler than the CIC estimate. The AUG-25 CDD total is 2nd coolest (for AUG) this century trailing only 2004 (254 CDD).