0% humidity? In California, it came close!

MT. DIABLO, Calif. -- Any hikers trying to climb to the Bay Area's Mt. Diablo better have had some lip balm.

An extremely dry air mass blew over the Bay Area at around the 3,000 foot level early Friday morning, dropping relative humidity to fractions of a percent, according to the National Weather Service.

The gauge started registering dew points (the temperature at which the air becomes 100 percent saturated) in negative values late Thursday evening, then dropped to ridiculous levels overnight toward dawn Friday. Around midnight, the humidity was about 1% with dew points around -11. Then an hour later, dew points crashed into the -40 range for a relative humidity of 0.62%.

It would get worse.

At daybreak the dew points crashed to an incredible -70 to -80 range, with a peak low dew point of -89 degrees! With an air temperature of 76 degrees, that calculates out to a humidity of 0.025 percent! What??!?

Now, it's possible with fractions that small the gauge can't accurately read the moisture content correctly at those extremely small amounts. A weather balloon launched in Oakland was reading humidity around 3% at those altitudes.

But still, no matter how you slice it, it was super dry up there. Good thing there is no carpet up there -- walking around in socks might have started forest fires!