Sacramento County Office of Emergency Services brought an update to its extreme weather Heat and Cold/Freeze Hazard Annexes before the Board of Supervisors yesterday that includes new risk assessments and probability tools from the National Weather Service to better coordinate severe weather response and improve earlier decision-making. The Board of Supervisors voted unanimously to adopt the new plans.
The Extreme Heat Hazard Annex and Extreme Cold/Freeze Hazard Annex are used to determine responses to severe weather events that impact county residents and infrastructure system-wide. While severe weather respite centers often welcome unhoused residents into their doors for relief from severe weather, the hazard annex is not a homeless-specific response and it is not a trigger for cooling/warming centers for the homeless. Rather the hazard annexes take into consideration extreme weather that impact public health risks to people, risks to animals and agriculture, and severe weather that may prolong power outages and make the effects of extreme temperatures worse through lack of heating or cooling.
These documents do not impact or limit a jurisdiction’s ability to open and operate weather respite centers or programs. Cooling or warming center operation is only one portion of the response activities identified in the plans.
Extreme heat events: Utilizing the Experimental HeatRisk Model offers an alternative, holistic solution that uses high and low temperature forecasts and adds data from Centers for Disease Control (CDC) heat health thresholds, local climatology, the duration of heat, and the heat island effect in urban areas. In the past, old heat temperature thresholds were solely based on the Heat Index.
- Old heat criteria:
- 3 days of 105 degrees day/75 degrees night
- Unusual human or animal mortality
- Temperatures combined with long-term power outages
- New heat criteria:
- Excessive Heat Warning from NWS
- 3 days of Magenta on the Experimental HeatRisk
- Unusual human or animal mortality
- Temperatures combined with long-term power outages
Extreme cold events: Adding the probabilistic data allows us to make decisions earlier with better certainty of meeting temperature thresholds. Earlier decision making improves communication to the public and logistics coordination to open warming centers and coordinate transportation.
- Old cold criteria:
- 3 days of abnormally low daytime temperatures and lows of 32 degrees or colder
- Unusual human or animal mortality
- Temperatures combined with long-term power outages
- New cold criteria:
- Previous criteria and adds:
- 50% probability or greater of reaching 32 degrees or lower over 3 days.
The new Sacramento County Office of Emergency Services Extreme Heat and Cold/Freeze Hazard Annexes can be
found on our website.