Expect a mixture of Mediterranean and Atlantic weather for Cadiz. This means a mild and moderate climate throughout the year. The sun is usually out, even on cool days, which translates to 300 days of sunshine a year.
The months of April to September are generally dry and comfortably warm, with temperature playing around the 25°C to 28°C range. Winters mean rainy days, never snow. At nighttime, wear those jackets! Though it is not as ice cold, the winds can make you feel quite chilly.
Internet Guide:
Cadiz Guide