No, you cannot. Hot and long days are not an excuse for not fasting. Only patients and travelers are allowed to postpone the fasting duty, yet they are advised to fast in Ramadan.
Allah the Almighty commands:
“The month of Ramadan in which was revealed the Qur’an, a guidance for mankind and clear signs of the right path. It lets discern right from wrong. So whoever of you sees that month, should spend it in fasting. (…)” (2:185)
If you think about the Muslims in the time of Muhammad, living in the deserts of Mecca and Medina where the temperature is around 50 degrees, campaigning in those days while fasting; you can understand that it is not so difficult to fast nowadays.