March 2025 Climate Forecast Discussion
March 2025 Climate Forecast Discussion for the period Apr-Jun through Jul-Sep 2025
**Note: ** The IRI seasonal forecasts of precipitation and temperature issued this month are based on an objective calibration procedure that combines the 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 February 2025, negative sea surface temperature (SST) anomalies declined over the central-eastern equatorial Pacific Ocean, leading to a NINO3.4 anomaly index value of -0.35 °C. Also, the weekly-averaged SST anomalies in the NINO3.4 region were 0.0 °C for the week centered on Mar 05, 2025. This indicates the weakening of the ongoing La Niña conditions in the equatorial Pacific Ocean. According to the early-March CPC ENSO forecast, a La Niña Advisory remains in effect, though ENSO-neutral is favored to develop in the next month and persist through the Northern Hemisphere summer (62% chance in June-August 2025). The Indian Ocean Dipole (IOD) index is neutral, and the North Atlantic Ocean continues to exhibit persistent warm sea surface temperature (SST) anomalies.
The IRI's seasonal precipitation forecasts issued in March 2025 indicate enhanced probability of above-normal probability for precipitation in the Central America, northern and west coasts of the northern South America, Southwest and Southeast Asia, the Maritime Continent region, and northern parts of Australia during Apr-Jun 2025. Conversely, substantially enhanced below-normal precipitation probability is forecasted for the southern and southwestern parts of the US, southern Chile, central Southwest Asia, and equatorial central and east Africa during the same period (Apr-Jun, 2025). The enhanced above-normal precipitation probabilities in northern North America and central and northern South America fade away in subsequent forecast seasons. Meanwhile, the below-normal probability areas in the Southern and Southwestern US gradually move northward and weaken gradually in subsequent seasons. Starting in May-July, the forecasts point to a gradually increasing probability of above-normal precipitation over the African Sahel and South Asia, as those regions enter their rainy seasons.
In terms of temperature, most land areas are projected to have a significantly higher likelihood of experiencing above-normal temperatures throughout the forecast period. However, the forecasts also suggest a slightly increased chance of below-normal temperatures in the African and Asian Monsoon regions. This is consistent with the precipitation outlook, which indicates above-normal rainfall during the Jun-Aug and Jul-Sep 2025 periods.