Hello dear native English speakers.

1. I don't care if it doesn't rain.
2. I don't care whether it doesn't rain.
3. I don't care if it rains.
4. I don't care whether it rains
5. I don't care whether it rains or not.
6. I don't care if it rains or not.
7. I don't care whether or not it rains.
Question:
Which is grammatically correct?
Do they have the same meaning?
I guess if 1# is grammatically correct , the speaker doesn't care the weather but perhaps other thing except the weather.
2# is grammatically correct but logically not thus wrong sentence.

Question

Hello dear  native English speakers.

1.  I don't care if it doesn't rain.
2.  I don't care whether it doesn't rain.
3.  I don't care if it rains.
4.  I don't care whether it rains
5.  I don't care whether it rains or not.
6.  I don't care if it rains or not.
7.  I don't care whether or not  it rains.
Question: 
Which is grammatically correct?
Do they have the same meaning?
I guess if 1# is grammatically correct , the speaker doesn't  care the weather but perhaps other thing except the weather.
2# is grammatically correct but logically not thus wrong sentence.

Answer

You might want to look this up, because I'm not sure about the rule, but I believe WHETHER should be used with a pair of possibilities.

Example:

I don't care whether it rains or not.  GOOD
I don't care whether it rains.     I THINK THIS IS INCORRECT, but some people might say it.
I don't care whether it doesn't rain.   INCORRECT, and UNNATURAL.

Answer

All are good except #2 and #4.

If you truly want to say that if it rains or if it doesn't it's all the same,  then #5 probably works best and #7 works well here as well.   #1 and #3 are okay but are a little akward souhding and lack some context to make better sense.

لا تفوّت فرصة تعلّم لغة جديدة وأنت مرتاح في منزلك. تصفّح مجموعتنا المختارة من مدرّسي اللغات ذوي الخبرة وسجّل في درسك الأول الآن!