Cascais, Portugal's climate is characterized by mild winters and warm summers. During winter months (December, January, February), temperatures range from around 3-20°C, with averages between 10-14°C. As spring approaches, temperatures gradually increase, reaching highs of up to 28-33°C in June and July. Summer months are warm and sunny, with average temperatures peaking at 21°C in August. Autumn brings a return to milder temperatures, ranging from 6-23°C, before cooler winter conditions set in once more.