I have a shower that is close to a toilet. Infrequently, when someone it taking a shower the toilet will eventually start bubling (with big bubbles). And it seems that usually afterwards the toilet will be clogged (sometimes the shower drain gets clogged too). After awhile, though, the clog usually resolves itself. Any clue as to what might be wrong, and how to fix it?

Not sure if the weather is related, but just in case: this only seems to happen in the winter, but I can't swear to that. It doesn't get that cold here normally in the San Jose area, but it is the rainy season here.

You have a partial blockage in the drain line. The solution is to snake the drain from the lavatory roof vent. Put out enough cable to reach the base and 15 foot more. Good luck, Tom