What would I do?

Ride to work like every other day. My boss wouldn't be amused if I called in on a chance of thunderstorms.

What's important isn't what I'd do, but why are you even considering not cycling?

Rain? Lightning? Being scolded for being out in the wet?

Rain: Before leaving the house, take a shower. If you melt, then stay out of the rain. And watch out for somebody dropping a house on your sister and stealing her shoes. Seriously though, with your forecast tomorrow, you have a 100% chance of getting wet from sweat. A 25% chance of rain? Hell, a 100% chance of rain would be a welcome relief.

Lightning: I'll never put down anyone for a deep psychological fear of lightning. But if it's the ordinary garden variety fright that the Weather Channel trumps up, eff 'em. Statistically, you’re far more likely to get squished by a dump truck in traffic on an ordinary day than you are to be hit by lightning. Yet you wouldn't post on the forum a question whether you should ride if there was a 25% chance of dump trucks on your way home, would you?

Plus, lightning isn't always lethal, even if that's the only time it's newsworthy. My family was tent camping in a water-access only site in Allegheny National Forest on the July 4th weekend in 1971 when we were hit by lightning in a t-storm at dawn. We all lived to tell. Although our dog didn't. And the tent was never the same.

Being scolded for being out in the wet: Eff 'em.

For the record, I don't even bother with a fendered bike if it's only a 25% chance of rain or t-storms.