This number probably includes things like swiping to the leftmost home screen on your phone to see the weather widget at the top. When it's that easy you can often check the weather unintentionally.
That's a 2009 study, so more like every time you open your flip phone.
Actually, now that I think about it, I have a weather complication on my watch–it's probably grabbing the weather every hour or so to keep it up-to-date.