Alicante is one of those Spanish vacation spots that you can explore all year long, so it depends on the kind of vacation you're looking for. Visit the city and neighbouring towns during the off-season to avoid crowds and oppressive heat. You can get better flight and lodging discounts if you travel on a budget.
Plan your journey to Alicante for the summer if you want to take advantage of the season and enjoy a livelier atmosphere. You can also go to many of the theme parks and waterparks that are only open in the summer during this period.