June 2025 Climate Forecast Discussion
June 2025 Climate Forecast Discussion for the period Jul-Sep through Oct-Dec 2025
**Note: ** The IRI seasonal forecasts of precipitation and temperature issued this month are based on an objective calibration procedure that combines four models NCEP-CFSv2, CanSIPS-IC4, COLA-RSMAS-CESM1, and NASA-GEOSS2S models. The climatological base period for normal is 1991-2020. The SST anomalies cited below refer to the OISST.v2.1 SST data set. Starting from June 2024, the observed climatology used to compute the dry mask was updated to 1991-2020, and the criterion modified to mask points where 10% of the training sample (i.e. 3 or more years) received less than or equal to 1 mm over a 3-month season.
During May 2025, sea surface temperature (SST) anomalies remain in the ENSO-neutral range over the central-eastern equatorial Pacific Ocean with the monthly NINO3.4 anomaly index value of -0.04 °C. The weekly-averaged SST anomalies in the NINO3.4 region were -0.0 °C for the week centered on June 04, 2025. This indicates persistence of the ENSO-neutral phase. According to the early-June CPC ENSO forecast, a “Not Active” ENSO Advisory was issued, with ENSO-neutral conditions favored during the Northern Hemisphere summer. The Indian Ocean Dipole (IOD) index is neutral, and the North Atlantic Ocean exhibit slightly warm sea surface temperature (SST) anomalies which have decreased substantially.
The IRI’s seasonal precipitation forecasts, issued in June 2025 for the July–September 2025 season, shows areas of the above-normal probabilities which are most pronounced in the Maritime Continent and Australia (Indonesia and Papua New Guinea), the central Sahel region of West Africa (from Senegal to Chad), interior eastern equatorial Africa; smaller areas of slightly increased probability of above-normal precipitation are also expected over parts of South Asia and NE Brazil. In contrast, below-normal precipitation probabilities are forecast across much of the Pacific coast of Central America (especially southern Mexico, Guatemala, Honduras, and Nicaragua), parts of the Andes and northern South America (including Venezuela and Colombia), the Pacific NW of the U.S./Canada, and scattered parts of southern Africa. Going forward, the significantly above-normal precipitation is consistently forecast for the Maritime Continent (especially Indonesia and Papua New Guinea) and northeastern Australia, with this wet signal persisting across all seasons. In contrast, northern South America, the Andes and SE South America shows a persistent and significant below-normal precipitation probability, as do parts of southern Africa and the Pacific coast of Central America. The Sahel region in West Africa and much of South Asia do not show strong or widespread anomalies, with only patchy areas of above- or below-normal signals, and large areas remain near normal or in the climatological range as the season progresses.
The temperature forecasts show a consistent pattern of widespread above-normal temperatures across most of the globe, with the strongest warming signals (dark red shades indicating 70%+ probability) persisting across much of North America, Europe, Asia, and northern Africa throughout all four seasons (JAS to OND). The few notable exceptions include small patches in central Asia that show near-normal conditions, and most significantly, parts of Australia that transition from above-normal temperatures in JAS to below-normal probabilities (blue shading) in the later SON and OND periods. The persistence of this warming signal across consecutive seasons suggests a strong underlying climate driver influencing global temperature patterns through late 2025.