Hungary has a continental climate, with cold, cloudy, humid winters and warm to hot summers. It is normally not much snow in Budapest, only a couple of days every year. In the winter the temperature has an average around 0 and -5 °C. The spring comes early, and is followed by a long summer. The summer of 2007 Hungary had almost two weeks were the temperature changed between 35 and 40 °C. In average it is between 27 and 35 in the summer. The autumn lasts until November, and then it normally gets colder and the temperature is between 0 and 8 °C. If you are interested in the average temperatures in Budapest, check out the table on the average temperature page.
All hotels with 4 or 5 stars and has air condition in the rooms, most of the 3 star hotels has, but it is always useful to check out beforehand, at least if it is important to you. During the summer it can always be nice with some air condition in your room.