I've been in a lot of really bad storms and survived. Batten down the hatches and do your best! A couple of times when a stake has pulled I've just pulled down the pole, wrapped up in the tent and waited out the storm.

Just to reiterate what's already been said: Lightning protection is really important! In the Rockies, it's best to plan your day so your exposed high altitude hiking is done in the morning and you're down off the heights by 1-2 pm. The storms may be daily or less frequent, but be ready for them to happen! If they don't, and you're where you can see thunderstorms start to form, then you can keep going. But be ready to head down at short notice.

And do watch those trees you're camped near or under, and never camp near dead, dying or leaning trees. A tree--or even a large heavy branch--falling on your tent--well, they're called "widow makers" for a reason!

For short trips, it's good to check the forecast. For longer trips, you really can't predict the weather more than a few days ahead, so you have to take what comes. Even if there's no rain in the forecast, I assume it will happen. Mountains make their own weather!