It's not advisable to travel either Rajasthan or Delhi in summer cos the temperature will be really very high & unbearable heat will kill all your excitement.It will be better if you travel somewhere around mid September or later as the weather will be very pleasant.
Specially if you are planning for a trip to Rajasthan.
Udaipur will be the best destination when visited during either early monsoons or during Feb
Its too hot in Delhi nd Rajasthan , i will suggest you to visit Delhi nd Rajasthan in between september to march. nd yes you can go to Mount abu, a hill station in Rajasthan, may be the weather there will not be that hot.