Rotterdam sää — lokakuu

Amsterdam forum regulars call October genuinely unpredictable — “can bring freezing cold or Indian summer, or all that in a matter of days” — with the first half of the month generally milder than the back half as autumn sets in properly. A light jacket covers most days, but nights start to cool down and by month's end can turn genuinely cold, with the swing running anywhere from 5°C to 20°C depending on the week. Rain isn't dramatically worse than other months — “not that much difference in rain” between September and October — but wind is “quite common,” so an umbrella is a coin flip against a proper rain shell. The reward for the back half: real autumn color in the parks. Our record: 15°C days, 10.5°C nights, 17.2 rain days and a 22.7kph wind — cool, wet more often than not, and blustery enough that the wind matters as much as the rain.

Forum posters describe January across the Netherlands, Rotterdam included, as capable of almost anything - temperatures anywhere between -15C and 15C, with varying degrees of rain, snow, or clear skies possible on a given day. Posters consistently recommend a proper winter coat, hat, scarf, gloves, warm sweaters and genuinely warm, weatherproof footwear regardless of forecast. Posters are direct that snow isn't guaranteed, and even when it does fall it typically doesn't stick around for long. Posters generally caution that forecasts here are only reasonably reliable about 2-3 days out, so treating a longer-range prediction as certain is a mistake. Posters generally rate January as workable for a Rotterdam visit with the right packing, but genuinely unpredictable day to day.

The Dutch line the forum keeps quoting for July is "if you don't like the weather, just wait five minutes" — and the numbers bear it out: around 22°C on average, but posters describe 28°C one day and 15°C the next, and sunny mornings turning to thunder by the afternoon. Rain lands on about thirteen days. Layers plus a small umbrella or poncho is the standing advice, with a big thin scarf as the adjustable extra. July is also crowded and pricier once the school holidays start. Rotterdam-specific: the bike paths, the harbour boat tours, Delfshaven and the water taxi all survive a shower.