Climatology
Climatology is a baseline forecast that predicts the historical base rate for every event. It is a standard benchmark for Brier skill score.
Definition
Climatology is a forecasting baseline that always predicts the same probability: the historical base rate for the event type or dataset.
Example
If events in your set resolve YES 30% of the time, climatology predicts p0 = 0.30 for every event.
Why it matters
Climatology is a strong baseline because it captures the dominant frequency. It is often used as the baseline in Brier skill score and can be much harder to beat than 50/50 when outcomes are imbalanced.
Related
Climatology is a special case of a benchmark based on base rate.