It could be because it is hot now so you sweat more, and well, you are just thirsty more as a result. When you use the bathroom to pee the color should be light yellow. If it is a darker shade of yellow. you are not getting enough water. Too light, like clear, might mean you are drinking too much water. Drinking too much water is a concern and can be dangerous because it dilutes your natural mineral balances in the blood, like sodium and potassium. However, you need to drink over a gallon or so a day for it to be an issue.
I don't want to alarm you, but another possible cause worth checking is diabetes. A doctor can check your A1C levels (blood sugar). Excessive thirst, especially after just drinking water, can be a symptom. You can even get a home test for it, but best to have a doctor do the testing.
