It is unlikely that the temperature will drop below 20°C, even at night. Most of the time is is between 22°C in the winter and 28°C in the summer. August and September can be really hot.
In the winter when the wind is blowing, you will need a light sweater at night, especially after several hours in the sun.

What is the best period for wind?
While you occasionally have wind all year long, the trade winds usually start blowing in mid-November until June. The wind is often light (14-20 knots) but is usually stronger from mid-January to March / April (up to 25-30 knots). We rarely get anything stronger than this.

What is best period for waves?
The first swells arrive in October and become more and more frequent. The biggest swells are from December to March. You can still catch a good north-west swell in April and May. In the summer you can sometimes catch some swell from the south, which are smaller but still great.

Do I need a wetsuit?
Yes - probably to protect you from the strong wind or the intense sun. If you are sensitive to the cold and want to ride all day then bring a 2/3mm shorty but a lycra rash shirt is enough for most people.