We use the first conditional to talk about a future situation that is possible.
|If the weather is nice tomorrow,||we will go to the seaside.|
The verb in the if-clause is in the present tense.
The verb in the main clause is in the Future Simple. (It doesn't matter which comes first.)
There is usually a comma between the two clauses:
This type of sentence implies that the action is very probable.
Note that the meaning here is present or future, but the main verb in the if-clause is in a present, not future tense.
Sometimes instead of if + present + future, we may have:
a) if + present + may/might (possibility):
If the climate keeps warming, the Arctic might be warm enough for swimming.
b) if + present + may (permission) or can (permission or ability):
c) if + present + must, should or any expression of command, request or advice:
d) When if is used to mean as/since, a variety of tenses can be used in the main clause.
Instead of if + present tense, we can have:
a) if + present continuous, to indicate a present actions or a future arrangement:
b) if + present perfect:
Talking about fulfiled conditions instead of if we can use when: