I regularly drink between 5 and 6 liters of water every day, today I drank more of that but I’m not sure why. And my routine has been the same without any significant changes.
Discussion
Heat can play a factor - we lose a lot more water on hot days then we realize. In general I wouldn’t be concerned about some daily variations in your habits.
If thirsts persists long term, one thing to note is that can sometimes be a sign of high blood sugar or insulin resistance. I’m no doctor though so I’d definitely get more professional advice if this is something which concerns you!