San Mateo County voters will decide on Tuesday, Nov. 3, whether to write climate preparedness into the county's founding document. Measure L, one of four County Charter amendments on the countywide ballot, would add a paragraph to the charter's preamble making long-term resilience to extreme weather a county priority. It passes with a simple majority.

What a yes vote does

The ballot question asks: "Shall the San Mateo County Charter be amended to add a provision to the Charter Preamble designating long-term resilience to extreme weather events as a County priority?" If approved, this paragraph would be added, according to the League of Women Voters' pros and cons summary:

"It shall be the policy of San Mateo County that long-term resilience against extreme weather events – including fire, flood, wind, rain, heat, drought, and sea level rise – is a County priority, to be undertaken collaboratively with cities, districts, and other public entities."

The current preamble, part of a charter adopted in 1932, says the people adopt the charter "to provide a local government responsive to our social, economic, physical and environmental needs and goals in a democratic, just and efficient manner."

What it does not do

The preamble is a statement of principles. The League says it does not create programs, departments, commissions or legal requirements, and no direct fiscal impact has been identified. KALW reports that supporters on the county's Charter Review Committee hope it raises public awareness and local urgency on climate action.

How it got on the ballot

Members of the county's Charter Review Committee, residents who applied or were appointed by their supervisor, drafted the language in April 2026, KALW reports. The charter must be reviewed at least once every eight years. In May, the Board of Supervisors passed a resolution placing it on the ballot.

The county's Sustainability Department says San Mateo County is already seeing coastal erosion, sea-level-rise flooding, landslides, heat waves, heavy rain, drought and more intense wildfires, KALW notes. The League adds that some reports rank the county among California's most vulnerable to sea level rise.

Who supports and opposes it

No one. No official argument for or against Measure L was submitted, and the League found no organized campaign on either side.

A no vote keeps the preamble as it is. For other Peninsula measures, see our San Mateo Measure H explainer and Redwood City Measure E, and every guide on our Nov. 3, 2026 election page.