SAN FRANCISCO (CBS SF) — We all know that San Francisco is one of the coolest spots in the country in the summer, but this May was much cooler than even the “average” chilly-ness.

The average high temperature in San Francisco in May was 60.2 degrees, more than five degrees cooler than normal.  More interestingly, May was cooler than January (61.9 degrees), February (65.9), March (67.5), and April (63.7).

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I looked back at the data for downtown San Francisco, and 2015 is the first year in the city’s history where the month of May had cooler afternoons that each of the previous four months.

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As you can see from the numbers above, it wasn’t even that close.  January was nearly two degrees warmer than May, and March was more than seven degrees warmer.

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Even in years where that May was cooler than 2015, there was at least one other month that winter & spring that was even cooler.  Not this year.  May 2015 was the coolest month of the calendar year, and will likely be the coolest month until this December.