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.