April 2026 Climate Forecast Discussion for the period May-Jul through Aug-Oct 2026
**Note: ** The CCSR/IRI seasonal forecasts of precipitation and temperature issued this month are based on an objective calibration procedure that combines the output from four models: NCEP-CFSv2, CanSIPS-IC4, COLA-RSMAS-CESM1, GFDL-SPEAR and NASA-GEOSS2S-2. 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 March 2026, sea surface temperature (SST) anomalies weakened further and settled within the ENSO-neutral category across the central-eastern equatorial Pacific Ocean, with the monthly Niño 3.4 index at 0.03 °C. Weekly averaged SST anomalies in the Niño 3.4 region were 0.2 °C for the week centered on April 08, 2026, indicating the persistence of values within the ENSO-neutral range. The early April CPC ENSO forecast, issued a Final “La Nina Advisory”, and maintained an “El Nino Watch”, with a transition to El Niño is likely in May-July with 61% chance, persisting through at least the end of 2026. (It is important to note that the ENSO monitoring and prediction issued by CPC is now based on the relative Niño 3.4 index.) The Indian Ocean Dipole (IOD) index is currently weakly positive, with a DMI value of +0.38 for the month of March 2026. The North Atlantic Ocean continues to exhibit slightly warm SST anomalies. The Pacific Decadal Oscillation (PDO) Index recorded a value of -1.44 °C in March 2026.
The CCSR/IRI objective Multi-Model Probability Precipitation Forecast for May–July (MJJ) 2026 indicates elevated odds of below-normal precipitation (yellow to brown shading) across parts of northern South America, Central America, the Indian Peninsula, and the Maritime Continent. This below-normal probability dominance persists strongly intensifies into Jun–Aug (JJA), Jul–Sep (JAS), and Aug–Oct (ASO), although the degree of intensification is spatially heterogeneous across regions. The current forecasts indicate a somewhat subdued Sahel and Southwest Asian summer monsoon, with predominantly white shading suggesting near-climatological probabilities. This pattern may be linked to the anticipated development of El Niño by that time, which is often associated with below-normal precipitation over these regions and may raise concerns for regional water resource management. During the forecast period, a slightly elevated probability of above-normal precipitation remains dominant over Türkiye and adjoining regions. In addition, a strong shift toward above-normal precipitation is evident during ASO over northeastern Africa, consistent with anticipated El Niño impacts on its short rainy season, while the North American monsoon region (northwestern Mexico and the U.S. Southwest) also shows an elevated probability of above-normal precipitation during the same period.
The temperature forecasts indicate that above-normal temperatures (red shading) are highly probable in most seasons across much of North America, northern and central Eurasia, the Middle East, Asia, and large portions of Africa and South America, consistent with a contribution from the anticipated El Niño state, while also reflecting global warming, recalling that the reference climatology is 1991-2020. In May–Jul and Jun–Aug, areas of below-normal temperatures (blue shading) are notable in parts of Southeast Australia. During Jul–Sep and Aug–Oct, parts of central North America including the northern United States and southern Canada tend to exhibit a tilt toward below-normal probabilities of temperature. This pattern extends across central-western band of Canada, the portions of the Great Plains, Upper Midwest, and Canadian Prairies (Alberta, Saskatchewan, and Manitoba), suggesting an enhanced likelihood of below-average conditions relative to climatology. Below-normal temperature probabilities in both central North America and southeast Australia reflect large-scale climate variability, including El Niño, but the mechanisms could differ by region.
