I wish it.....

No, they are not all saying the same thing.

1) I wish it wasn't raining. (Or I wish it weren't raining.)
This implies that at present, it is raining.

2) I wish it didn't rain.
This suggests that the speaker either objects to the phenomenon of rain in general or at a specific time in the past.

3) I wish it wouldn't rain.
This is similar to #2 except that the wish is extended into the future.

4) I wish it wouldn't be raining.
This sounds incomplete — the speaker needs to state when.

Examples 2 and 3 would function correctly if accompanied by an explanatory clause.

2 )I wish it didn't rain when I forget to bring my umbrella.
Attending the festival was fun but I wish it didn't rain.

3) I wish it wouldn't rain every time I go camping.

Example 4 seems clumsy and could only be used in a particular context:

4) If I had one wish to make about my vacation, I wish it wouldn't be raining.

Hi aok after some 80+ years in the trade I vaguely 'mem' this'n's wrong; s/b 'weren't' ??

Help, someone

Oh but d'anuuone catch the pun

Yes, but it's dropping out of use.

S'okay Paok, bue we'd say, '4) I wish it weren't raining'


/// tho we might also say, 4) 'Wish it wasn't rainin'