September Seasonal Model Update – Looking Toward Winter 2025–26

Today’s ECMWF seasonal model update keeps the weak La Niña in play a bit longer. Instead of fading quickly, the latest run holds it through at least January, with neutral conditions not expected until mid to late February.

Here’s what the maps are showing:

• Nov–Dec–Jan: Greens light up across northern California and into the Sierra. That often points to more storm action and a better shot at early season snowpack.

• Jan–Feb–Mar: The green retreats north, and browns (drier signal) spread south. That lines up with a more front-loaded winter — busier early, quieter later.

Take a look at the ECMWF maps below — green shades highlight wetter than normal trends, while brown shades mark drier signals.

September runs are always a key checkpoint. If the Sierra stays painted green again in October’s update, confidence grows for a solid early season. For now, it’s encouraging to see the signal lean our way.

Snowman