Along with other Bay Area cities, Berkeley experienced a significant heat wave last week as temperatures rose into the upper 80s and low 90s degrees Fahrenheit across the Bay Area on Thursday.
According to campus biometeorology professor Dennis Baldocchi, a high-pressure system over the western United States causes air to heat up and diverge toward the coast. Last week, the high-pressure system was far enough inland that coastal cities did not experience the typical cooling effects of ocean proximity, a mechanism that typically explains why Bay Area heat spells in September and October, according to Baldocchi.
“These things happen all the time but this is definitely an extreme,” Baldocchi said. “And these extremes are happening more and more with global warming.”
Baldocchi added that the Bay Area has experienced unprecedented dry weather this year, which may have amplified the heat as moisture tends to cool air.
Darren Peck, a meteorologist with KPIX 5, said dry air is also a consequence of heat waves, with hot weather as one of the leading culprits in drying out the California landscape, presenting an alarming wildfire risk.
“It’s not a problem for the immediate fire risk now, but where we really feel that is several months down the road when you start to get into late summer and fall,” Peck said.
Last week’s heat wave caused a record-breaking loss of statewide snowpack — which was already at historically low levels — diminishing from 37% April 1 to 22% as of Monday, according to Peck.
Peck added that while last week’s heat wave alone doesn’t present immediate risk, heat that diminishes snowpack can gradually impact the state’s water supply. Melted snow typically fills California’s reservoirs, but water managers are no longer able to rely on this, Peck said.
“Now, for water managers, they cannot count on that water coming in the late summer because the snowpack is melting so much earlier than it used to,” Peck said.
According to Michael McCormick, staff lead at the Bay Area Climate Adaptation Network, nighttime temperatures have been rising in the Bay Area, which poses its own concern. When urban spaces can’t fully cool down at night, there may be local health implications related to the body getting too hot, McCormick said.
McCormick noted that rising temperatures in the Bay Area present a wide variety of planning and policy concerns, such as air conditioning in buildings, air quality and the impact on unhoused people.
“It affects so many different parts of society, so many different people and the infrastructure we rely upon,” McCormick said.