The exclamatory form for 'It is a + adjective + noun' follows: 'What a(n) + adjective + noun + it is!'. So 'It is a lovely weather' becomes 'What a lovely weather it is!'. Option 1 matches this pattern, despite a minor spelling typo of 'weather'.
Note: Option 1 contains a typo ('wealther' instead of 'weather'). We have selected it as the intended correct exclamatory transformation.