Summer (June–August)
The peak season for first-time visitors: long days, warm weather, a packed festival calendar and busy beaches on the Curonian Spit. Vilnius and Kaunas are at their liveliest, but expect higher hotel prices and book Nida or Palanga at least 6–8 weeks ahead.
Long summer evenings suit walking and food tours; winter is the time for Christmas-market visits and museum-led indoor itineraries.
Spring and autumn (April–May, September–October)
The shoulder seasons give you noticeably fewer tourists, mild weather and lower hotel prices. The easiest window for walking-led trips around Vilnius Old Town, the lakes, and the historical castles. Late September is often warm and dry.
Winter (December–February)
Vilnius Christmas markets are among the best in Europe and the city looks remarkable under snow. Cold (often below −5°C) but atmospheric, dramatically quieter than summer, and good value once the holiday peak passes in early January.