An analysis of 478 cities by GeoRank looked at the number of daylight hours each year considered comfortable for spending time outdoors, taking into account heat, humidity, cold, rain and wind.

The results put Portuguese cities in a particularly strong position when it comes to summer heat.

Porto loses just 42 daylight hours a year because of excessive heat, the lowest figure among the four Portuguese cities included in the comparison provided by GeoRank.

Lisbon follows with only 58 hours lost to heat, while Braga records 141 and Coimbra 219.

The difference becomes particularly noticeable when Portugal is compared with some of Europe's best-known summer destinations.

Barcelona loses 210 hours a year to heat, Málaga 320 and Athens 742. In Seville, the figure rises to 886 hours, while Catania in Sicily records 885. Antalya in Turkey loses 1,034 daylight hours a year because conditions are considered too hot.

Porto stands out in July

The data also looks specifically at how much daytime can comfortably be spent outside during the summer.

Porto records 423 comfortable daylight hours during a typical July, compared with 378 in Lisbon, 392 in Braga and 370 in Coimbra.

By comparison, Barcelona records 368 hours and Málaga 320.

The difference becomes much greater further into the Mediterranean. Athens has 191 comfortable hours during July, while Seville has 158, Catania 144 and Antalya only 110.

This means Porto offers more than twice as many comfortable July hours as Athens and around 2.7 times as many as Seville under GeoRank's methodology.

The results suggest that Portugal's Atlantic location can provide an advantage during the hottest part of the year. While temperatures are still warm enough for summer holidays, extreme heat takes away considerably fewer daytime hours than in many Mediterranean destinations.

Portugal does not come first everywhere

The results are favourable for Portugal, but the country does not take the top spot in every comparison.

Northern Spain performs particularly well during summer. Bilbao records 438 comfortable daylight hours in July, while Oviedo has 434, both slightly ahead of Porto.

Portugal also falls behind several Spanish destinations over the full year.

Lisbon records 3,473 comfortable outdoor hours across a typical year, compared with 3,574 in Las Palmas, 3,569 in Málaga and 3,491 in Alicante.

The wider picture therefore points towards the Atlantic coast performing particularly well during summer, rather than Portugal simply having the most comfortable climate in southern Europe.

What does a "comfortable hour" mean?

The figures should not be confused with the number of sunshine hours a city receives.

GeoRank calculates how many daylight hours have conditions it considers suitable for being outdoors, then separates unsuitable periods into hours lost because of heat, cold, rain, or wind.

For heat, the calculation uses apparent temperature, meaning it considers humidity alongside air temperature.

The thresholds used to decide whether conditions are comfortable are set by GeoRank and are not an official meteorological standard.

The data is also based on 1981–2010 climate normals, meaning it represents typical historical conditions rather than the weather experienced in Portugal during this particular summer.

GeoRank's wider climate methodology uses several meteorological and climate datasets and includes calibration against weather stations. Its methodology page lists sources including WMO and national meteorological services, alongside ERA5 and satellite climate data.

Despite these limitations, the comparison highlights an interesting feature of Portugal's summer climate: while the country enjoys plenty of warm weather, its major cities lose relatively little outdoor time to excessive heat compared with many competing Mediterranean destinations.

For visitors who want warm summer weather without spending the hottest part of the day indoors, that could be one of Portugal's less obvious advantages.