Climate Prediction Center - Week 3-4 Outlook

Prognostic Discussion for Week 3-4 Temperature and Precipitation Outlooks
NWS Climate Prediction Center College Park MD
300PM EDT Fri Aug 21 2026

Week 3-4 Forecast Discussion Valid Sat Sep 05 2026-Fri Sep 18 2026

The El Niño Southern Oscillation (ENSO) Alert System Status is set to El Niño Advisory. Equatorial sea surface temperatures (SSTs) are above average across the central and eastern Pacific Ocean. The atmospheric circulation anomalies over the equatorial Pacific Ocean are consistent with El Niño. El Niño is strengthening, with a greater than 90% chance of a very strong event during the Northern Hemisphere fall and winter 2026-27.

The strong El Niño continues to be the major influence on anomalous rainfall and tropical convection. During mid-August, the Madden-Julian Oscillation (MJO) began to constructively interfere with the strong El Niño. The MJO is expected to propagate eastward over the Western Hemisphere during late August and then shift back to the Indian Ocean in September.

An equally weighted blend of dynamical and statistical forecast tools features an anomalous ridge in the 500-hPa geopotential height field centered over the west coast of Canada and the border between central Canada and the north-central United States. This ridging pattern stretches across most of Alaska and the contiguous United States (CONUS).

The dynamical models generally agree on above average temperatures across most of CONUS and Alaska during the outlook period. The models disagree on the temperature outlook for parts of the West Coast and the Great Lakes region. Equal Chances are forecast where signals are weak or mixed for this outlook period.

The dynamical models generally agree on above average precipitation across the Southwest, Northern Rockies, and parts of the West Coast and below average precipitation in the Northeast and Middle Atlantic seaboard. Equal Chances are forecast where the signal was weak or mixed for the outlook period.

For Hawaii, the outlook favors above normal temperatures and above normal precipitation for all of the islands.

Forecaster: Emerson LaJoie

The next week 3-4 outlook will be issued on Friday, Aug 28, 2026

These outlooks are based on departures from the 1991-2020 base period

These are three category outlooks consistent with what is currently used for the monthly and seasonal forecasts.

The shading on the temperature map depicts the most favored category, either above-normal (A), below-normal (B), or near-normal (N) with the solid lines giving the probability ( >33%) of this more likely category (above, below, or near).

The shading on the precipitation map depicts the most favored category, either above-median (A), below-median (B), or near-median with the solid lines giving the probability ( >33%) of this more likely category (above, below, or near).

In areas where the likelihoods of 2-week mean temperatures and accumulated precipitation amounts are similar to climatological probabilities, equal chances (EC) is indicated.