Het weer in Olbia (Costa Smeralda) in september

Regulars trade a small risk for a large gain and say so plainly: September carries more chance of a cloudy or wet day than July or August, and in exchange the beaches are close to deserted and everything else is easier to get. The water, they argue, is actually at its best now and stays warm enough to swim until the end of the month - our row has it at 23.8C. Their one caveat is wind, which our 18.8 kph average supports. Days at 28.4C over 16.6C nights make for the evening chill they mention: warm in the sun, a jacket after dark. Rain is the smaller half of the bargain at 58.9mm across 5.9 days. The record: humidity 72 percent, 10.6 hours of sun and AQI 48.

Sardinia's forum describes January as the island's coolest month but genuinely variable - some posters had lovely sunny days with cold, clear nights (no cloud cover to trap any warmth), while others visiting in the same general window hit cold, wet and windy stretches instead. A clear midday can reach a pleasant high-teens C before dropping off fast into the afternoon and evening, but freezing temperatures are unlikely on the coast around Olbia. It's not remotely beach weather, but a mild, walkable winter month when you catch the good days.

Forum posters describe July around Olbia and northern Sardinia as very pleasant for swimming, with daytime temperatures usually above 30C and sea temperatures around 24-25C, though posters flag a real risk of jellyfish this time of year. Posters consistently recommend packing a light wind or rain jacket and a light sweater for the evening despite the summer heat, since coastal evenings can turn noticeably cool. Posters also note Sardinia runs windier in summer than other seasons, a real factor for anyone planning beach days or boat trips. Posters generally rate July as calmer and less crowded than August, making it their preferred pick between the two peak summer months.