Faro has a hot-summer Mediterranean climate , moderated by a transitioning Portugal-Canary current giving a certain resemblance to Southern California that is not heated in the summer by the Mediterranean Sea like Algarve. Given this region is highly susceptible to the difference of precipitation throughout the seasons of the year, in the future scarcity of water could appear in conjunction with the increase of temperature and less incidence of rains.
Summers are warm to hot and sunny with average daytime maximum temperatures of 27–35 °C (81–95 °F). Summer warmth can linger well into October. The weather in the winter is generally mild by European standards, managing around 6 hours of sunshine each day, with temperatures averaging around 8–16 °C (46–61 °F) in the coldest month. The city receives most of its rainfall over the winter; rain is scarce between June and September. The annual average temperature is around 17.5 to 18.5 °C and the annual rainfall is around 500 millimetres (19.69 in). The average sea temperature is 16–17 °C (61–63 °F) in January rising to 22–24 °C (72–75 °F) in August and September. Higher sea water temperatures are reached if the weather patterns produce a significant outflow of warmer surface water out of the Mediterranean which bathe the coastal Algarve with much warmer water.
With over 3000 hours of sunshine a year, Faro is often regarded as the sunniest city in Europe. July and August are the sunniest months and December the dullest.