Thessaloniki weather in September

September is the month regulars recommend for this coast and the reason is thermal: the sea has had all summer to warm and is at its best now, while the crowds of August have gone and the resorts are winding down. Our column reads 27.2C of water against 29.7C of air, which is the rare case of a sea nearly as warm as the day. Rain is light at 36mm across 6.7 days and humidity is a comfortable 65 percent. Their one hedge is the end of the month, which can turn chilly. The city's own beaches are a bus ride out along the gulf rather than in the centre. The record: 16C nights, 10.4 hours of sun, an 11.1 kph wind and AQI 45.

Regulars call this genuinely mixed weather, layering-required with a warm jacket still worth packing, though days are reliably above freezing and often sunny between cooler, wetter stretches. Our row backs that transitional read, 16.9C over 4.1C nights feeling 2C, with 79.5mm of rain across 12 days and a trace of leftover snow, 1cm. Regulars are consistent this counts as off-season here, a real upside flagged specifically for shopping - noticeably fewer crowds and better sales than the summer rush - alongside indoor museum days like the Archaeological Museum and Museum of Byzantine Culture recommended for whichever days turn cold and wet. The sea stays cold at 10.9C, not swimming weather. The record: humidity 74 percent, 8.7 hours of sun, an 11.6 kph wind and AQI 43.

Regulars call mid-September to mid-October the best stretch in this city and describe October as a bit chilly rather than cold, with a few rains and not many - our row agrees at 48.3mm across 5.6 days. Their range, mid-twenties down to the mid-teens, brackets our 23.1C over 10.5C, and their packing note is precise: a couple of sweaters, and an overcoat would be an exaggeration. They do warn the sea is too cold for most, where our row reads 24C, so take their word on the water only if you are not used to it. What they sell is the quiet - few people, a light breeze, autumn colour. The record: humidity 73 percent, 8.2 hours of sun and AQI 39.

April in Thessaloniki is a month that has not decided yet. Regulars describe it swinging between glorious sun at 23 to 25C and chilly rain at 14 to 15C, with the monthly average landing near 14C and rising noticeably towards the end - our row's 22.1C average high is the good half of that spread, its 7.8C night the other. Whatever the day does, they say, the evening will be chilly. The date that shapes April here is Greek Easter, which moves year to year: Good Friday brings the procession of the Epitaphios from the metropolitan church, and the holiday closes things around it. The wet count is real too, our row giving 9 precipitation days against their eleven. The record: 58.4mm of rain, 10.6 hours of sun and a 14.8C sea.

Thessaloniki forum threads describe January as genuinely cold for a Greek city, with posters citing real low temperatures and reports of heavy snow in some years. The damp, humid cold was described as harder to shake than a dry cold of the same number, with waterproof boots called a real necessity given the genuine chance of snow in the city itself. A practical tip repeated across threads: many accommodations lack proper heating, so posters recommended confirming heating is included before booking a January stay. Despite the cold and wet stretches, posters were positive about visiting regardless - museums and archaeological sites stay open, and even the outdoor cafe culture continues under heat lamps for those who prefer it to going fully indoors.