October through April is the sweet spot — temperatures hover between 20–25°C, the lake is warm enough to swim, and the jet-ski traffic is manageable. Winter brings a steady population of snowbirds from Canada and the northern United States who fill the campgrounds and give the town a lively low-key atmosphere.
Spring break (late February through March) is frenetic — the Strip around London Bridge becomes a party zone for university students from Arizona State, UCLA, and schools across the Southwest. The lake fills with boats and the noise is considerable. Come for this or avoid it entirely depending on your preference.
Summer (June through September) is genuinely brutal — temperatures regularly exceed 43°C (110°F). Even serious boaters limit their time on the water to morning hours. If you must come in summer, arrive at dawn, be on the water by 7am, and retreat to air conditioning by noon. The evenings cool to a still-hot 30°C.