The best time to visit Chania is May to June or September to October, when temperatures are warm (24–28 °C), the sea is swimmable, and the old town and beaches are far less crowded than in peak summer.
Spring (April–June): April can still be cool and the Samaria Gorge may not yet be open (it typically opens in May). May and June are ideal — wild flowers are blooming, the gorge is open, Elafonisi is gorgeous, and you can book a harbour-view room without months of advance notice.
Summer (July–August): Peak season. Temperatures regularly hit 32–35 °C, Elafonisi and Balos are very busy, and accommodation prices peak. Still a fine time to visit if you book early and plan beach trips for early morning.
Autumn (September–October): The sea is at its warmest (still around 24 °C in September), crowds thin dramatically after mid-September, and tavernas are less frantic. October brings occasional rain but remains largely warm and pleasant.
Winter (November–March): Chania quietens significantly. Many harbour restaurants close, but the city carries on — the Agora, the old town, and the museums are open. Prices drop sharply. A good choice for budget travellers happy with cooler, occasionally rainy days and no beach swimming.