Please see the corresponding ‘Discussion‘ item for each Regional Forecast Map which provides a detailed explanation of the Forecast. Included with some of the older forecasts are ‘validation maps’ generated from data provided by NCEP/CPC.

The ‘Discussion‘ for each region also contains tables of the rainfall cutoffs used between near-normal, above-normal, and below-normal rainfall in terms of percent normal rainfall. In addition, there are maps of the maximum and minimum extremes for rainfall in each region.

Observed Data is only available for the regional precipitation maps, later than 3 months preceding the current forecast.

A Global Extremes map is also provided, which indicates perceived risk that the seasonal precipitation will fall into the wettest/driest 15th percentile of the observed records.

View the Seasonal Climate Verifications Pages.

The climatological base period used is 1981-2010.

The IRI net assessment is a multi-institutional product made in collaboration with COLA and GFDL.  When using IRI forecasts or related data please cite both the published paper describing the dataset and the datasets themselves.  Read more about our forecast system, collaborators and recommended references for citation here.