Help with this weather commentor please

here is what i have so far
program Weather21;
var weather: char;
begin

writeln ('please type b for bad weather or g for good weather:');
readln (weather);
if weather := 'b'
then
writeln ('hope the weather improves')
else
writeln:= ('enjoy the nice weather');
end.

This is meant to ask whether the weather is good or not and then make a comment mad using dev-pascal please help