Summer officially begins today, with low temperatures all over Portugal

June 21 sees the official start of summer, with Portugal registering unusually low temperatures in all regions. Forecasts point to this changing dramatically from tomorrow, with hot weather set to return within three to four days. June 21 is the year’s ‘longest day’, bringing with it (despite the low temperatures)  14 hours 53 minutes and eight seconds of daylight (one second more than the country enjoyed on Sunday).