Weather in Kos in May

How May compares

May is the 6th warmest month of the year in Kos and ranks 101st of 134 destinations we compare for May - see where else is hot in May. Within Greece it is 24th of 44 (Greece in May). Against London's average high of 16.6°C in May, Kos is 4.4°C warmer by day and 9.5°C warmer at night.

Daytime and night-time in May

The typical May day in Kos peaks at 21.0°C, but that is an average: the warmest 10% of days reach 23.6°C or more. Roughly 1 in 20 days top 25°C and 1 in 250 pass 30°C. Nights average 17.8°C; one night in ten drops to 15.5°C or lower, so pack a layer for evenings. Between 1991 and 2020 the hottest May day here reached 34.2°C (2020-05-17) and the coldest night 12.2°C (1997-05-02).

Rain in May

Some rain (4-8 rainy days): about 3 days with 1 mm or more, 16 mm in total. Year to year it varies a lot - the wettest May was 1991 with 50 mm, the driest 1999 with 0 mm. Humidity averages 77%.

Sea temperature in May

The sea averages 19.4°C - bracing (18-22°c). Depending on the year it ranges from 18.5°C to 20.3°C. For the warmest sea here, come in August (25.2°C).

Sunshine and daylight

Around 10.4 hours of sunshine a day (estimated from cloud cover), 14.0 hours of daylight: the sun rises about 06:03 and sets about 20:11 local time in mid-May. Average cloud cover is 26%.

Is May a good time to visit Kos?

It is a reasonable choice: warm days. The best months for Kos on our scoring are August, July, June; months averaging 25°C or more: Jul, Aug, Sep.

Comfortable daytime warmth, with a layer for evenings

Expect weather that suits walking around and sitting outdoors more than a holiday built around high temperatures. The average daytime high is 21°C, and only 5% of days reach 25°C, so reliable heat is not May's strength. That makes it a reasonable choice if you find hotter weather tiring, though sunshine still calls for sun protection and shade when needed. Nights average around 18°C, but the coldest 10% fall to 15.5°C or below. Light daytime clothes plus a jumper or light jacket give you more flexibility than packing for summer alone. For outdoor evening meals, keep that extra layer handy rather than assuming it will stay warm after dark.

Plenty of daylight, but the sea is still bracing

There is plenty of scope to spend the day outside, with about 10.4 hours of sunshine within 14 hours of daylight. Rain is a possible interruption rather than the main concern: about 3 days have measurable rain, so leave some flexibility in your plans without expecting a washout. Swimming needs a more cautious judgement. The sea averages 19.4°C, with a year-to-year range of 18°C to 20°C, so even a sunny afternoon does not mean warm water. If you enjoy a brisk dip, it may suit you; if you want to linger comfortably in the sea, May is less convincing. A towel and a dry layer are sensible things to have ready afterwards.