Faro, where it lies

In Faro, the capital of Algarve, the southernmost region of Portugal, the climate is Mediterranean, with mild, relatively rainy winters and warm, sunny summers. There are beautiful beaches, where you can also surf in the ocean.
Here are the average temperatures.
Faro - Average temperatures
Min (°C)91011131418202019161310
Max (°C)151618202225282826221916
Min (°F)485052555764686866615550
Max (°F)596164687277828279726661

Precipitation is not abundant, since it's lower than 500 millimeters (20 inches) per year, and follows the Mediterranean pattern, in fact, it's more abundant from October to March, while it becomes rare in April and May, and almost absent in summer. Here is the average precipitation.
Faro - Average precipitation

The wind blows frequently: in the cold half-year, it is caused by Atlantic depressions, while in summer, sea breezes blow in the afternoon.

Winter, from December to February, is mild, and it's characterized by sunny periods, alternating with periods of bad weather, with wind and rain. Very cold days are rare: the temperature drops to freezing (0 °C or 32 °F) only in the coldest nights, but even in these cases, it typically rises above 10 °C (50 °F) during the day.

Spring, from March to May, is mild and sunny. In March and the first half of April, there may still be a bit of instability, with some rain.

Summer, from June to mid-September, is warm and sunny. During some days, there are cool, "Atlantic" weather conditions, with highs around 20/23 °C (68/73 °F) in June, and 24/26 °C (75/79 °F) in July and August, while at other times, when the wind blows from Africa, there can be hot days, with highs around 35 °C (95 °F). However, sea breezes temper the heat.

Autumn, from September to November, is initially warm and sunny. In September, the first disturbances may occur, but they are still rare. Still in October, there are many warm and sunny days, especially in the first half of the month. By November, we are well into autumn, actually, the weather is mild, but it's also often cloudy and rainy.

Beach in Algarve

The amount of sunshine in Faro and Algarve is excellent in late spring and summer, from May to August, while it is acceptable in autumn and winter, when in addition to sunny periods, cloudy and rainy days are possible. Here are the average sunshine hours per day.
Faro - Sunshine

The Atlantic Ocean is never very warm to swim in, and it is still a bit cold in June, when the water temperature is about 19 °C (66 °F), then it goes up to 20 °C (68 °F) in July and to 21 °C (70 °F) in August and September. Here are the average sea temperatures.
Faro - Sea temperature
Temp (°C)161516161719202121201817
Temp (°F)615961616366687070686463

Best Time

The best time to visit the cities of Algarve, for walks and hikes, is the spring, in April and May.
The best time for a beach holiday is instead the summer, from June to mid-September. It's better to bring a sweatshirt for cool and windy evenings, especially in June and September, but for safety also in July and August, especially if you are sensitive to cold.