I would create a function like this:
CREATE DEFINER = 'root'@'localhost' FUNCTION `getSeason`(P_date DATE)
RETURNS varchar(10) CHARSET latin1
DETERMINISTIC
CONTAINS SQL
SQL SECURITY DEFINER
COMMENT ''
BEGIN
DECLARE v_season VARCHAR(10);
DECLARE v_month integer;
DECLARE v_day integer;
select date_format(P_date,'%m'),date_format(P_date,'%d') into v_month,v_day;
if (v_month<3 or (v_month=3 and v_day<21)) then
set v_season="Winter";
else if (v_month<6 or (v_month=6 and v_day>=21)) then
set v_season="Spring";
else if (v_month<9 or (v_month=9 and v_day>=21)) then
set v_season="Summer";
else if (v_month<12 or (v_month=12 and v_day<=21)) then
set v_season="Autumn";
else
set v_season="Winter";
end if;
end if;
end if;
end if;
RETURN v_season;
END;
And use the function in your WHERE clause: where getSeason(myDaeField)='Winter'
Or in your select :
select getSeason(myDateField) as Season