Northern Lights (Tromsø) in April

September through March offers aurora potential, but October through February gives you the best odds. Peak season runs December through February with 19+ hours of darkness daily. But crowds peak then too, and temperatures drop to -15°C. November and March offer good darkness with milder weather around -5°C. Avoid the summer months completely - Tromsø experiences midnight sun from May through July with no darkness for aurora viewing. Check aurora forecasts on the Aurora Service website before booking. Clear skies matter more than high aurora activity levels.