United States
The official outlooks, the models underneath them, and a straight answer about where American seasonal forecasts are worth acting on. Being paved — the reference routes below are open now.
What this lane will carry
Route 02 · Route 07Official
The CPC outlooks
NOAA's Climate Prediction Center issues the United States' official monthly and seasonal outlooks on the third Thursday of every month, as tercile probabilities for temperature and precipitation, plus a seasonal drought outlook. They are the benchmark — not a competitor.
Dynamical
The NMME behind them
Eight coupled models from NOAA, NASA, GFDL, NCAR and Environment Canada, pooled into roughly a hundred members. The NMME is the single most useful thing to put next to a CPC map, because it shows you how much of the outlook is agreement and how much is one model.
European view
SEAS5 over North America
ECMWF's system covers the United States too, on a different model core with a different set of biases. Where SEAS5 and the NMME agree over North America, that is worth something; where they disagree, that is worth more.
Where US seasonal skill actually lives
Be honest about thisWinter temperature over the southern and eastern United States, in a year with a well-developed ENSO event, is about as good as mid-latitude seasonal forecasting gets — the Pacific jet is being pushed by something the models genuinely predict. Winter precipitation across the southern tier and the Pacific Northwest inherits the same signal.
Summer precipitation over the Corn Belt, by contrast, is close to unforecastable three months out, and any product that implies otherwise is over-selling itself. The useful summer signal is in soil moisture and the trend, not in the circulation.
Temperature outlooks almost everywhere carry a large and unglamorous contribution from the warming trend. That is real skill and it counts — but a site ought to tell you when the model is adding to it and when it is just riding it.