I always skipped checking my window seals because I thought our dry climate meant it was not needed. Last spring, we had those crazy dust storms that blow in from the west. I started finding fine sand on every surface inside my house. It got so bad that my allergies acted up, and cleaning became a daily chore. After talking to a neighbor, I found out that tight seals can keep most of that out. I spent a weekend caulking and weather-stripping all my windows. The difference was huge; no more dust piles on the sill. Now I make it a point to check seals every fall, and I tell everyone to do the same.