Vienna is warm and sunny in May and June, and in September and October; July and August can be hot and stormy, with temperatures reaching into the high 90s°F. From November through March winter can get cold, with snow falling in January and February; lows of 10°F are frequent.
Culturally, high season in Vienna is May, June, and September, when festivals, marathons, concerts, and operas are in full swing. The ball season December to February offers everyone a chance to brush up on his or her footwork and the many Christmas markets attract crowds from all over the world.
Many Viennese leave the city in July and August, so the city tones down some, though this is also when you might find discounted rates at hotels.
In Vienna the biggest Christkindlmarkt (Christmas Market) goes up in November in the plaza in front of the city's Rathaus (town hall); there are more than 20 smaller ones dotted around town (including outside Schönbrunn and the Belvedere Palace, in the Spittelberg Quarter on the Freyung square, and in front of Karlkirche on Karlsplatz).
The New Year opens in Vienna with the concert by the Wiener Philharmoniker Orchestra (01/505-6525. www.musikverein.at); reserve a year, or more, in advance. Those who can't get into the Philharmonic concert can try for one of the performances of the Johann Strauss operetta Die Fledermaus or another light delight in the Volksoper (01/513-1513. www.volksoper.at) or at the intimate Kammeroper (01/513-1513). The New Year is marked by an array of balls, such as the Kaiserball (01/587-3666-14. www.kaiserball.at), held in the elegant rooms of the Hofburg.
On January 6 children disguised as the Magi walk the streets, especially out in the country, knock on doors, sing a song and recite poems about coming from afar, and ask for a small donation.
Fasching (or Fasnacht, as it's called in the western part of the country), the Carnival period before Lent, in February, can become very wild, with huge processions of disguised figures, and occasional unwilling participation by spectators, who may even suffer (light) blows. In Vienna, which is comparatively quiet at this time, the ball season, which officially begins in November but gets into swing in late December or early January, lasts through Shrove Tuesday (Mardi Gras). The biggest society event is the Opernball (Opera Ball)), held at the Staatsoper (01/514-44-2606. www.staatsoper.at).
The Wiener Festwochen (www.festwochen.at) —a festival of theater, music, films, and exhibitions—takes over Vienna from mid-May to mid-June.
September 1 marks the start of Vienna's theater and music season.