At the opposite end of the spectrum in Klagenfurt, the smallest of the eight Swiss and Austrian venues hosting the finals, soaked fans cowered in doorways to avoid the rain.
"We can get the weather right, you can't, you can't," sang a group of German supporters, whose country saw weeks of sunshine and high temperatures during their hosting of the 2006 World Cup, taunting nearby Austrian football fans.
In Zurich, Switzerland's largest city, more than 10,000 feverishly followed the championship via public viewing.
But Andy Richardson, Al Jazeera's correspondent in Switzerland, said the match was "not the awe-inspiring opening the Swiss supporters would have been hoping for".
Saturday's results saw the Czech Republic score a 1-0 victory over Switzerland, while Portugal won a 2-0 victory over Turkey.
A brief scuffle between Swiss and Czech fans ended without incident but police later pulled two people out of the crowd and detained them.
About 40,000 people visited the Geneva fan zone to watch the big screen broadcasts of Switzerland playing the Czech Republic in Basel, while Portugal took on Turkey just a few hundred metres away at Stade de Geneve.
Captain in tears
In some rather lacklustre football in Basel's Saint Jakob-Park, Switzerland lost Alexander Frei, its captain and leading scorer, to a knee injury.
The 28-year-old striker was taken off the field in tears shortly before halftime and returned to the bench on crutches.
Frei was taken off the field shortly before
halftime with a knee injury [Reuters]
The Czech Republic's offence stagnated in midfield and the European Championship opener looked headed to a dreary draw until Vaclav Sverkos came off the bench to score his first international goal and give the Czech team a 1-0 victory.
"It was the best moment of my football career," said Sverkos, who was making only his third appearance for the national team.
"I was trying to shoot as soon as possible because the defender was coming."
But Czech midfielder Tomas Galasek admitted after the match that his 20-metre headed pass to Sverkos was not necessarily intended for the striker. Sverkos then mis-hit his shot.
Switzerland controlled the match for long stretches, but missed a chance to equalize in the 80th minute.
Tranquillo Barnetta's low shot was stopped by Czech goalkeeper Petr Cech after defender Tomas Ujfalusi appeared to handle the ball in the area.
Switzerland's Johan Vonlanthen got the loose ball but his shot hit the crossbar, and the chance was over.
Until then, there had been few clear-cut scoring chances, with the youthful Swiss team lacking a cutting edge in front of goal and the experienced Czechs happy to soak up pressure and look for chances on the counterattack.
Portugal v Turkey
Over in the Stade de Geneve, Pepe and Raul Meireles scored second-half goals to give Portugal a 2-0 win over Turkey.
Brazil-born central defender Pepe, playing in his first major competition for Portugal, scored from inside the area after a one-two with striker Nuno Gomes. He beat defender Emre Asik to the ball and sent a right-footed shot into the net.
|Turkey supporters had less to smile about|
after losing 2-0 to Portugal [AFP]
Meireles added another in injury time after Cristiano Ronaldo began a late break, then passed to Joao Moutinho, who got the ball back to Meireles for the goal.
"I can hardly describe the emotion I'm feeling," Pepe said.
"We played as a real team and that's important. We knew sooner or later we would score a goal.
Today, I must stress that it was the team spirit that prevailed. We deserve to be congratulated for our great display."
The victory comes as a boost for Portugal, which is hoping to repeat its successful campaigns at Euro 2004 and the 2006 World Cup.
Turkey, in its first major competition since reaching the semifinals of the 2002 World Cup, will have to recover to keep alive this year.