The phrasal verbs practice 01

NOTE: The second version isn't really the future. The future would be something like: I will drive to my aunt's tomorrow. It will rain heavily, which is unusual this time of year, so I will slow down.

NOTE 2: "an aberration in this season" is gramatically correct, but not a natural word choice. Try something like "which is unusual this time of year."

The phrasal verbs practice 01

3. Present:
I always prefer to slow down when I caught in an unexpected downpour on the road.

1. "Rainy weather is not typical per se, but it does happen sometimes." "He doesn't like running per se, but he will go for a jog if you ask nicely." "It is not the salt per se that is the important ingredient." Usually we use "per se" with the word "not" before it: Rainy weather is NOT typical... He doesN'T (short form for does not) like running... it is NOT the salt...

I would look up more uses of "per se" for reference. It is used by some people, but not very often.

2. This sentence is not really future tense. You are talking about the future, but adding "what if" makes it conditional. When you have to add the word "would", "could" or "should" the sentence becomes conditional. A better way to write in the future would be to take out the "what if" and the "I'm wondering".

I will go to my aunt's house even if it rains hard and I'll get there late.

If you want it to be conditional you could write:

If it rains hard on my way to my aunt's house, I would slow down even if it means being late.

or

What would I do if it downpours on my way to my aunt's? I would slow down even if it means being late.

In these types of sentences, I find it unusual to mention that it doesn't typically rain in this season, but someone else may find a better way to add that in.