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Seasonal Forecasts

Temperature and precipitation outlooks on seasonal (multi-month) timescales.

Forecast

Current seasonal temperature and precipitation outlook maps and discussion. Released on or about the 15th of each month.

Using the forecast maps

Use the controls above each map to choose what it shows. On the seasonal page you can pick the forecast Source, the Type (precipitation or temperature) and the date the forecast was issued. On the subseasonal page you pick the Type, then the year, month and day of issue. The map updates as soon as you change a setting. The box of buttons on the map switches between the forecast periods in that issuance: target seasons on the seasonal map, forecast periods on the subseasonal map. The title changes to match the period you pick. You can zoom with the scroll wheel or the +/– buttons and drag to move around the map. Download PNG saves the period currently shown as an image, with its title and legend.

CCSR/IRI NMME Multi-Model Probability Forecast for Precipitation for
August-September-October Issued July 2018
Probability (%) of Most Likely Category
Below Normal
40
45
50
60
70+
Normal
40+
Above Normal
40
45
50
60
70+
Dry Season (No Forecast) Equal Odds

July 2018 Climate Forecast Discussion

July 2018 Climate Forecast Discussion for Aug-Oct through Nov-Jan2019

The SST forecast shows weak El Nino conditions developing for the initial Aug-Oct season, intensifying to moderate strength (>1.0C in the Nino3.4 region) by Oct-Dec and Nov-Jan. Much of the subtropical and extratropical North Atlantic and North Pacific SST, as well as the SST in much of the mid-latitude Southern Hemisphere, are predicted to be above-average during all four forecast seasons. Exceptions are noted in the very high latitudes north of North America and south of South America, where below-average SST is predicted for all four forecast seasons. A positive Indian Ocean Dipole is predicted for all four forecast seasons. Slightly above-average SST is predicted for the tropical Atlantic for all four seasons, especially in the south tropical Atlantic.

Strongly enhanced probabilities for below-normal precipitation are predicted for Central America, the Caribbean islands, Indonesia and eastern Australia for Aug-Oct, and for Indonesia, the Caribbean and eastern Australia for Sep-Nov. A tilt of the odds toward below-normal is also forecast for Indonesia, much of Australia, central Africa, northern South America and the Caribbean for Oct-Dec, and for Australia, Indonesia and northern South America for Nov-Jan. Enhanced chances for above-normal precipitation are forecast for part of the African Sahel and Gulf of Guinea for Aug-Oct, for eastern equatorial Africa for Aug-Oct through Nov-Jan, and for the southern U.S. and/or Mexico, central-southwest Asia and part of northern Asia for Oct-Dec and Nov-Jan.

Enhanced probabilities for above-normal temperature are predicted for varying parts of Greenland, Asia, Europe, northern or southern Africa, Australia, North America and South America from Aug-Oct through Nov-Jan. The tilt of the odds toward above-normal averages weakest in Australia and South America in Aug-Oct, North America in Oct-Dec, and Africa in all four forecast seasons. Enhanced probabilities for below-normal temperature are relatively scant, but do appear in part of central North America in Oct-Dec and Nov-Jan. An enhanced likelihood for near-normal temperature is predicted for a small part of northeastern South America and central and northwestern Africa mainly for Aug-Oct and Sep-Nov, and for Africa’s Guinea coast and south-central Africa for Nov-Jan.

Citation

Kirtman, B., D. Min, J. Infanti, J. Kinter, D. Paolino, Q. Zhang, H. van den Dool, S. Saha, M. Mendez, E. Becker, P. Peng, P. Tripp, J. Huang, D. DeWitt, M. Tippett, A. Barnston, S. Li, A. Rosati, S. Schubert, M. Rienecker, M. Suarez, Z. Li, J. Marshak, Y. Lim, J. Tribbia, K. Pegion, W. Merryfield, B. Denis, and E. Wood, 2014: The North American Multimodel Ensemble: Phase-1 Seasonal-to-Interannual Prediction; Phase-2 toward Developing Intraseasonal Prediction. Bull. Amer. Meteor. Soc., 95, 585–601, doi: 10.1175/BAMS-D-12-00050.1.