Mine does this too. Very frustrating. It reset Sunday before 7 pm. However my week was not done. I exercise in the evenings. So it throws my tracking off. I have searched and it looks like there is no way to correct it. Strava should fix this so it resets at midnight. 

Mine does this too. Would love a resolution.

Mine seems to reset at midnight. 

Perhaps double-check the location you’ve set up in your profile. Sometimes people enter a city name and Strava auto-selects the rest (state/country), but if you're e.g. in Melbourne, Florida and Strava thinks you're in a Melbourne in Victoria, it will put you in a different time zone (and will reset your weekly progress early).