*Sea surface temperatures drop markedly during past year across the all-important tropical regions*
April 21, 2025 Paul Dorian
Water temperatures have dropped off markedly during the past year or so in tropical regions around the world. Sea surface temperature anomalies of a year ago (left plot) have in most tropical regions transitioned from above-normal (shown in orange) to nearly neutral conditions of today (right plot). Maps courtesy Canadian Met Centre
Overview
While global sea surface temperatures continue to run at above-normal levels, there has been a rather dramatic cooling trend across tropical regions all around the world. During the past year or so, water temperatures in the Indian Ocean have dropped to nearly neutral levels around India and well above-normal levels immediately east of Africa have moderated to only slightly above-normal conditions. In the central part of the tropical Pacific Ocean, relatively neutral water temperatures have replaced the El Nino conditions of a year ago when water temperatures were as much as two degrees higher than normal. Perhaps the most dramatic change in water temperatures has taken place in the tropical Atlantic Ocean where much warmer-than-normal conditions of a year ago are virtually normal as we approach the end of April and there is even a pocket of colder-than-normal water just off Africa’s west coast. The tropics are a critically important part of the world with respect to the total energy budget and cooling trends can certainly have an inhibiting impact on the upcoming tropical season.
The “Main Development Region (MDR)” of the Atlantic Ocean has been in a long-term downward trend that began early in 2025. Water temperatures are now right near the neutral line as we approach the summer tropical season on the Atlantic Basin. Map courtesy NOAA, tropicaltidbits.com
Details
Water temperatures across the world’s tropical regions have generally trended downward during the past year or so and, in some cases, there has been quite a dramatic turnaround. The theories on the tropical cool down range from fluctuations due to natural oceanic cycles to changes in underwater volcanic activity (credit Meteorologist Joe Bastardi of Weather Bell Analytics on this theory) and this can include the possibility of waning effects from the 2022 Hunga-Tonga eruption which was an extremely large volcanic event in the South Pacific.
https://arcfieldweather.com/blog/2025/4/21/interesting-trends-in-sea-surface-temperatures-with-quite-a-drop-off-across-the-tropicspotential-ramifications-on-the-upcoming-tropical-season
