I've asked for that thing before and I relatively solved the issue. What I still notice is that every time the hour gets modified due to that daylight saving time -you know, going back and forth one hour to "save energy"- my stats get modified.
I mean the visits that occur from 11pm till 1 am get moved from one day to another due to what I think is the way to calculate days.
We assume that every year has 365 days of 24 hours each day. And once every four years we have 366 days of 24 hours each. But that's not exactly true. Regular years have 363 days of 24 hours, one day of 23 and one of 25. Last weekend of March, when clock reaches 2am on Sunday it becomes 3am. We jump an hour, so that day on March has 23 hours. And in the last weekend of October it happens the other way. At 3 am it's 2 am again, so that day it really has 25 hours. Note that the number of hours per year are exactly the same as 365x24=(363x24)+(23+25).
I know it sounds weird (and could sound even more weird due to my English), but it is how it works. And here is where WP stats come to subject. I guess the system calculates visits and visitors in periods of 24 hours (which is normal), so when that irregular days come, the visits and visitors from "the frontier hours" (11 pm to 1 am) get moved back and forth as I say at the beggining.
I have no solution to that "issue" and it's not such a fatal bug, but I'd wanted to point it out for if it could be fixed.
The blog I need help with is postexcavatorix.wordpress.com.