The duration cannot be known with certainty when a watch or shutoff begins. It depends on:
- How long extreme weather and wildfire-risk conditions continue along the transmission corridor;
- Changing forecasts and real-time field observations;
- Whether crews can safely access and inspect the line;
- Terrain, smoke, darkness, road conditions, and aircraft availability;
- Whether wind has brought trees or debris into the line during the shutoff;
- Whether equipment was damaged during the shutoff and needs repair; and
- Power-system conditions required for safe re-energization.
A PSPS may end quickly if risk conditions change, or it may last many hours or even days if high-risk conditions don’t improve or system inspection or repairs are needed.