Start with the three categories
CPC seasonal outlooks divide temperature and precipitation into three categories: above normal, near normal and below normal relative to the 1991–2020 climate normals. The map shows which category has the highest forecast probability.
A 50% “above normal” area does not mean 50% warmer
It means the above-normal category has roughly a 50% forecast probability for the three-month average or accumulation. It does not mean every day will be warmer, that temperatures will be 50% higher, or that half the season will be above normal.
“Equal chances” does not mean normal weather
Equal chances (EC) means CPC does not have enough forecast skill to favor one of the three categories over the climatological baseline. The season can still end up very wet, dry, warm or cool.
Seasonal precipitation is not snowfall
Precipitation includes rain and snow water. A wet signal cannot be converted directly into a snow forecast. Temperature, elevation and individual storm tracks determine precipitation type.
Use the exact valid period
OND, NDJ, DJF and JFM are overlapping three-month windows. The signal can strengthen, weaken or move between them. Local Winter Outlook therefore treats its regional cards as a broad cold-season baseline and uses your selected window only for timing context unless the source clearly supports a more specific change.
Forecasts get superseded
CPC issues a new long-lead set each month. The site stores the issue date and shows an update-check warning after the next scheduled release so an older snapshot does not quietly present itself as current.
Best workflow
- Use ENSO strength to understand the large-scale background.
- Use the latest CPC seasonal map for your exact three-month window.
- Use historical El Niño patterns only as context.
- For a real trip, storm or safety decision, switch to current weather guidance days—not months—ahead.
Primary source: NOAA CPC Long-Lead Seasonal Outlook Discussion ↗.