What timezone WIP streaks is based on?

Just realized that, my timezone and WIPs timezone could be diferent, and I don't know what timezone WIP streaks are based in. 

It just passed mid-night for me, and I completed a task and this question came. 

I think the streaks follow the timezone in your settings:
When you open the website from another location, it also asks if you want to update your timezone

@gvrizzo is right. The streak is based on the time zone of your account settings.

The rest of the site however is based on UTC.

Thanks @gvrizzo and @marc for the clarification. :)