If you read the FAQ, you'll find that the daily and monthly totals shown are "rolling totals" meaning however many views for that time period from right when you look at the stats going back however much time is what you see. So if you get a lot of traffic in one twenty-four hour period, it will go up, but when you traffic slows down later, the numbers will appear lower.
Only your "ever" stats accumulate "forever."
Besides the counters here are just plain mechanical and even count your own views. For more accurate stats with a lot more info, you'll want to use Analytics.