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San Francisco weather: Hotter heat waves in near future

Hang onto that fan you just bought

Bay Area Experiences Record Temperatures In First Heat Wave Of The Year Photo by Justin Sullivan/Getty Images

This week will be cooler in San Francisco, with the sheltering gray hand of Karl the Fog helping shell-shocked San Franciscans recover Labor Day weekend’s desert-like climate extremes recover.

But the future beyond our 10-day forecast likely holds more temperature extremes than San Francisco has experienced in its recorded history.

San Jose State University meteorologist Alison Bridger warned NBC Bay Area this week that recent record-breaking temperatures are not a new status quo; the new status quo will be worse.

“Here’s the old normal, here’s the new normal,” Bridger explained, demonstrating with upraised hands. “We’re somewhere in between. We haven’t finished changing yet.”

The high pressure influx that drove thermometers mad across the bay last weekend has not moved on from the region in spite of lower temperatures this week, Bridger adds.

These are not new predictions. Back in 2015, the San Francisco Department of Public Health’s climate profile report cited some sizzling future stats based on current climate change models that should give pause to already heat-weary locals:

  • Average yearly temperature may go up by as much as 6.2 degrees by the year 2100.
  • The city may experience as many as 90 additional days each year on average hotter than 85 degrees. Currently we usually only have about 10 such days annually.
  • Droughts and dry spells will increase, but so too will wild and unpredictable storms, with a projected 11 percent rise in extreme “Pineapple Express” deluges.
  • Consequently, so called 100 year tides will begin to occur more frequently than just every 100 years on average.
Augustine Lim

A July 2012 study by the California Energy Commission acknowledges that it’s tricky to measure and predict weather and temperature patterns in San Francisco. However, the study also notes that there’s no qualified analysis that doesn’t acknowledge that temperatures are rising:

Historically, extreme warm temperatures in the San Francisco Bay region have mostly occurred in July and August, but as climate warming takes hold, the occurrences of these events will likely begin in June and could continue to occur in September (Figure 6).

All simulations indicate that hot daytime and nighttime temperatures (heat waves) increase in frequency, magnitude, and duration from the historical period and during the projected period through the first half of the twenty-first century.

And the city’s 2014 hazard plan about potential future heat-related crises cited ominous precursors already in the record books:

The July 2006 California heat wave, which was felt in San Francisco, was the largest heat wave on record since 1948. During the hottest day of that four-day event, San Francisco experienced temperatures over 100 degrees Fahrenheit.

On that day, the daily emergency medical system call volume for San Francisco more than doubled due to heat related health impacts throughout the city.

No word yet on how the Labor Day flash-fry compared to the 2006 burn, beyond the fact that it broke all previous heat records. But note that even a single day of triple-digit temperatures was itself remarkable just barely more than 10 years ago.