July 2025 Climate Forecast Discussion for the period Aug-Oct through Nov-Jan 2025/2026
**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, GFDL-SPEAR 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 June 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 +0.1 °C for the week centered on July 09, 2025. This indicates persistence of the ENSO-neutral phase. According to the early-July CPC ENSO forecast, a “Not Active” ENSO Advisory was issued, with ENSO-neutral conditions favored during the late Northern Hemisphere summer. Thereafter, chances of La Niña conditions increase into the fall and winter 2025-26, but remain comparable to ENSO-neutral. 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 Multi-Model Probability Forecasts issued in July 2025 provide a global outlook for precipitation probabilities across four overlapping seasons: August–October (ASO), September–November (SON), October–December (OND) 2025, and November 2025–January (NDJ) 2026. Across these periods, the most prominent areas forecasted for above normal precipitation (marked in shades of green to blue, with probabilities of 45% or higher) are consistently found over Indonesia, parts of Papua New Guinea, and northern and eastern Australia, particularly from August to December. These regions show strong and persistent signals of notably wetter conditions. Some portions of the western Pacific also suggest increased probabilities for above normal rainfall. Conversely, below normal precipitation (shaded in yellow to brown, with similar probability thresholds) is prominently forecasted across northeastern South America (especially northern Brazil, Venezuela, and Colombia), eastern equatorial Pacific coastal regions, southern Africa, and portions of Central Asia and the Horn of Africa. Parts of southern South America and west-central North America also show elevated chances for drier than normal conditions in several seasons, especially from September 2025 through January 2026. Seasonal shifts are visible, but the strongest and most persistent signals—above normal in maritime Southeast Asia and below normal in northern South America—persist through all forecasted months. The maps also indicate large regions with climatological odds (white) and some with no forecast due to the dry season (pink: MENA region), signaling areas where precipitation climatology or seasonal dryness limit predictive confidence. Most, though not all, of these precipitation patterns are consistent with the forecasted high odds of La Niña, which is shown to have probabilities comparable to ENSO-neutral, especially during the fall and early winter months.
The IRI Multi-Model Probability Forecasts for temperature, issued in July 2025, indicate a persistent and widespread probability for above normal temperatures globally from August 2025 through January 2026, 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 (ASO to NDJ). There are only isolated, minor regions where probabilities for below-normal temperatures appear, most notably in limited parts of interior Asia or far southern South America, and these are generally weak and inconsistent. The persistence of this warming signal across consecutive seasons suggests a strong underlying climate driver influencing global temperature patterns through late 2025.
