Low humidity levels

Low humidity levels generally 30% and below

High winds

Forecasted high winds above 20 mph and gusts above 30-40 mph

Fuel conditions

Condition of dry material on the ground and vegetation near lines

Red Flag Warning

A Red Flag Warning issued by the National Weather Service

Observations

On-the-ground, real-time observations

PG&E’s decision-making process is evolving to also account for the presence of trees tall enough to strike power lines when determining if a PSPS is necessary.