If you are coming here for a holiday any time from October to May bring a jacket and jumper and coat for the nights and just in case there are some cold days.
The other thing to bring to Alicante Airport in the winter is slippers as the marble floors can turn your feet into blocks of ice!
In the summer bring cool clothes, as unless you are very unlucky you certainly will not need a jacket for the evenings.
Alicante is covered by hills and mountains in the north which means the weather is a kind of microclimate with a limited amount of rain and the average temperature even in winter time does not often fall below 16°C.
You can sunbathe virtually everyday from May to the beginning of October. Sunbathing is possible all year round but between November and May you can get some quite cold winds. However if it is sunny then it is warm enough to sit in the sun for at least for 2 hours per day – even at Christmas!
Below is a climate chart showing the average monthly temperatures in Alicante:
You definitely need a car with air conditioning from March until October, but take a view on it from November until February.
The weather in Alicante really is hot enough for you to put the air conditioning on during the spring and autumn months. Most of the Alicante hire cars come with it for a small amount extra.