I'm heading up to the Desolation Wilderness (Lake Tahoe Sierras) and forecast is calling for 40% of T-Storms both days. I usually don't bring rain pants but every other trip has had clear forecasts.

Typical Clothing:
Patagonia Wool 2 Zip Neck
Nylon Hiking Pants - Mountain Hardware
ExOfficio Give-N-Go Boxer Briefs
Wright Socks (two pair)
North Face Diad Jacket
Eddie Bauer Midweight Baselayer Pants (Microgrid fleece similar to Patagonia R1)
Wool Buff
Montbell U.L. Parka

I could bring my REI Taku Pants - but they're quite heavy 25.4oz Manuf. weight. Or I could run around town to find some DriDucks pants somewhere.

I don't mind getting my pants/shoes wet so long as the pants have some time to dry out. I can always retire to the tent with my midweight pants if it gets too cold and still by dry.

My storm pants weigh 2.5 ounces, so they go on almost every trip. If the weather gets cold or windy or wet, they go on in an instant.

--B.G.--

Depends on how cold it is. If it is cold enough that shorts are too cold and you find yourself wearing pants, you are not going to be happy when they get wet and cold. If you are wearing shorts everywhere, then it's probably not a big deal if they get wet.