The weather in Cuba is hot, sunny and tropical, with an annual average temperature of 24°C. The hottest months are July and August, when the average daily maximum rises to around 32°C. The weather is coolest in January and February, with average daily maxima of 26°C. Nights become significantly cooler than the day, and some people may even think the sea is not warm enough for swimming.
The dry season begins in November and lasts through to early May, with lots of days with clear blue skies. Even so, rain can come at any time. In Cuba's wet season, from May to October, there may be two or three days with rain in a typical fortnight. But the rain does not usually last long - coming in short sharp bursts that clear quickly.
The high season for visitors is from mid-December to mid-March. It's best to book well ahead at this time of year if you can. Although the busiest hotels may be fully booked there is usually a decent choice of reasonable alternatives. Cubans take their annual holidays in July and August.
The Caribbean hurricane season formally begins in June and is most active in September and October. Some years have fewer hurricanes than others, but the chance of actually being affected in a two week trip is fairly low. Cuba is well-prepared for hurricanes and looks after its visitors efficiently and safely. The storm generally passes in 2-3 days and the drama compensates in some measure for the inconvenience. Electricity and water are usually cut off while the storm lasts, with no air-conditioning and no water other than bottled water for drinking. At worst you may well find yourself evacuated to safer but less pleasant accommodation until things blow over.