Novosibirsk has a sharply continental climate. Winters are brutal — January averages around -19°C, and -40°C is not unknown. Summers are warm and short: July averages around 20°C and can push to 35°C in a heatwave. There is no spring to speak of; the city goes from mud to summer in a matter of weeks.
The best time to visit is June to August, when the Ob Sea beaches are in use, the parks are green, and the cultural calendar is full. The Opera and Ballet Theatre is active through the winter season (September to June), which is the other compelling reason to visit — though getting around in January temperatures requires planning and good boots. Autumn (September–October) is brief and beautiful, with the birch forests around Akademgorodok turning gold.
The Siberian-Cossack Expo and various cultural festivals in summer provide additional reasons to visit in the warm months. The New Year celebrations in January are elaborate and involve elaborate decoration of the central squares, which is atmospheric if you can stand the cold.