Present Simple+ Future Simple
Incorrect : If it will rain tomorrow, I shall not go to college.
Correct . If it rains tomorrow, I shall not go to college.
Note : If we talk about a realistic future event in a conditional sentence, the conditional clause should be in the present simple and the principal clause in the future simple tense. In place of ‘shall/will’ in the principal clause, other modals like can, may or must can also be used.
For example:
If she invites me, I can/may/must attend the party.
However, the 'if' clause may also be in the future tense if you make a request.
For example:
I shall be grateful if you will lend me some money.