I have read about the importance of weep holes with aluminum storm windows, but we have several old wooden storms in our house. Do those naturally drain because they're not airtight, or is some kind of weep hole needed?
You will see weep holes in aluminum storm windows when the frame is projecting from the exterior wall and has a "lipped" edge. The weep holes allow drainage that otherwise would not occur because of the lipped frame edge. Wooden storm windows are usually hinged and set flush with the frame. The frame bottom is normally beveled so as to shed water away from the interior. If you have weather-stripping installed on the storm windows that creates a good seal it may be wise to modify it if you see water entering past the storm window.