Sea surface temperatures off the north-eastern coast of Japan are tipped to be up to +1.5C above average in the Asia Pacific Western North Pacific Basin, with implications for typhoon activity, according to Moody’s Risk Management Solutions (RMS) 2023 outlook.     

The report also predicts waters around the South China Sea and the Philippines will be up to +0.5C above average. Sea surface temperatures across the basin, between July and November, will be near or above average. 

“Warmer sea surface temperatures typically enhance tropical activity by providing increased energy and moisture to the environment,” Moody’s Chief Risk Modelling Officer Mohsen Rahnama said. 

Typhoon activity in the Western North Pacific Basin will be above average due to shifts in the El Nino Southern Oscillation (ENSO) and an increase in atmospheric instability, the report says. ENSO forecast models generally favour the development of El Nino conditions during the Northern Hemisphere summer.  

Most of the Western North Pacific typhoon season activity usually occurs between May and November. 

Turning to the North Atlantic, Mr Rahnama says after nine hurricane landfalls in the past three years people are concerned to know if the 2023 North Atlantic hurricane season, from June 1 to November 30, will ease. 

He says the latest forecasts are for a near-normal season, due to the competing and opposing influences of such factors as the ENSO and above-average North Atlantic sea surface temperatures. 

The National Oceanic and Atmospheric Administration (NOAA) forecasts a 70% probability that the 2023 hurricane season will produce: 12–17 named storms, five to nine hurricanes, and one to four major hurricanes.