The Costa Blanca ("White Coast"), the part of the Spanish southern coast belonging to the province of Alicante, has a Mediterranean climate, with mild, relatively rainy winters and hot, sunny summers. Because of its southeast exposure, the Costa Blanca has a mild and sunny microclimate. There are towns like Denia, Javea, Moraira, Calpe, Altea, Benidorm, Villajoyosa, El Campello, Alicante, Elche, Guardamar del Segura, Torrevieja.
The daily average temperature ranges from about 12 °C (53.5 °F) in January and February to about 26 °C (79 °F) in July and August. There are many sunny days, with daytime temperatures reaching or exceeding 20 °C (68 °F) even in winter. In winter, very cold days are rare, but on colder periods the minimum temperature can drop to about freezing; in practice, it never snows. The coldest records are around -2/-3 °C (27/28 °F). In summer, the heat is generally bearable and sea breezes blow, but there may be periods of intense heat, when the temperature can reach as high as 38/40 °C (100/104 °F).
Here are the average temperatures of Torrevieja.  

The rains in the Costa Blanca are scarce, since they are even lower than 300 millimeters (12 inches) per year, and follow the Mediterranean pattern, in fact most of them occur from September to March, while in summer it almost never rains. Rainy days are particularly rare, but when it rains, it can rain a lot, and sometimes the rains may be intense and concentrated in time, causing floods. Owing to the scarcity of rainfall, the landscape is arid.
This is the average rainfall in Torrevieja.

The amount of sunshine in the Costa Blanca is decent in winter, when Atlantic or Mediterranean disturbances can sometimes affect this area; however, there is a good number of sunny days (there are on average 6 hours of sunshine per day even in January). Spring is a sunny season, especially in May. The sunniest period is from June to August, when clear skies are the norm. In September, there are the first Atlantic fronts, so in autumn the sun is not always guaranteed.
Here are the average daily sunshine hours in Alicante.



The sea in the Costa Blanca is warm enough for swimming from July to September; in June, it's still cool. Here, for example, are the temperature of the sea near Benidorm.

Best Time

The best time for a beach holiday in the Costa Blanca is the summer, from June to August. The water temperature is comfortable enough from July to September, although in September, which overall is still a good month (especially in the first half), the first Atlantic fronts begin to show up. May and June are sunny months, but the sea is still a bit cool, especially in May, when it is actually a bit cold.
Even though good weather is not always guaranteed, spring and autumn are ideal for visiting cities and going on excursions to the interior, as in summer the weather can be very hot.