Ischia weather: climate and temperatures month by month
Air temperature, sea temperature and rainy days, month by month: the real data to know what to actually expect before you travel.
Ischia has a mild Mediterranean climate all year round: winters almost never drop below 7°C, summers stay warm but tempered by the sea, and hotel thermal pools work regardless of the season. Here's the real data, month by month: air temperature, sea temperature and rainfall.
Ischia's climate in brief
Ischia sits in the Gulf of Naples and has a Mediterranean climate tempered by the sea: temperature swings are limited, winters are mild (rarely below 6-7°C) and summers warm but less stifling than the Campania mainland. The full swimming season runs from June to late September, but hotel thermal pools stay warm all year, regardless of outdoor weather — one of the reasons the island stays alive even in the colder months.
Air temperature and rainfall figures are long-term climate averages (from the nearest reference station, the island of Capri, with an almost identical climate); sea temperature is a month-by-month historical average.
Ischia month by month: the full table
- January — air 7-13°C, sea ~15°C, rainfall ~69mm
- February — air 7-13°C, sea ~14°C, rainfall ~57mm
- March — air 8-14°C, sea 14°C, rainfall ~57mm
- April — air ~11-17°C, sea ~16°C, rainfall ~39mm
- May — air 14-22°C, sea 19°C, rainfall ~34mm
- June — air 18-26°C, sea 22°C, rainfall ~16mm
- July — air ~21-28°C, sea ~25°C, rainfall ~12mm
- August — air ~22-29°C, sea 26°C, rainfall 38mm
- September — air 18-26°C, sea 24°C, rainfall ~45mm
- October — air 15-22°C, sea 22°C, rainfall ~70mm
- November — air 12-17°C, sea 19°C, rainfall ~102mm
- December — air 9-14°C, sea ~16°C, rainfall ~87mm
Values marked with a tilde (~) are estimates consistent with the month's trend, where month-by-month point data isn't available; the others are the climate averages cited throughout the article.
Winter (December-February): mild, rainy, thermal spas take the lead
Winter in Ischia is mild by Italian standards: average temperatures stay between 7°C and 14°C, with December slightly warmer (9-14°C) than January and February (7-13°C). The sea sits between 14°C and 17°C, too cold for swimming, and it's also the rainiest period of the year alongside November: around 87mm of rain in December, 69mm in January, 57mm in February. It's the season when the island slows down the most — many properties close — but the thermal pools of the hotels that stay open work as always, warm water regardless of the outdoor temperature.
Spring (March-May): temperatures rise, the sea warms up
From March to May, air temperatures rise steadily, from 8-14°C in March to 14-22°C in May, while rainfall drops progressively: 57mm in March, 39mm in April, just 34mm in May. The sea is still too cool for proper swimming (14°C in March, 19°C in May), but it's one of the best periods for the island's trails — Monte Epomeo included — and for the outdoor thermal spas, with comfortable outdoor temperatures and no crowds.
Summer (June-August): the peak of heat and sea
June brings the first truly summery days (18-26°C, sea at 22°C), but August is the hottest month of the year: temperatures up to 29°C and the sea at its peak, 26°C. July is also the sunniest month, with clear skies around 90% of the time. Rainfall is at historic lows: just 16mm in June, among the lowest figures of the whole year, rising slightly again in August (38mm).
Autumn (September-November): the sea stays warm, then the rain arrives
September extends summer: 18-26°C and the sea still at 24°C, almost as in June — we cover this in detail in our guide to weather in Ischia in September. October drops gradually (15-22°C, sea at 22°C) but remains a fully liveable month, especially for those seeking thermal spas without crowds. November is the real change of season: temperatures 12-17°C, sea at 19°C and the rainiest month of the year, with around 102mm of rain. From here on, the thermal spas, not the sea, become the reason to come to the island.
Which month is best for you
It depends on what you're after: those wanting the warmest possible sea look to August, those wanting it without the crowds aim for June or September, those coming mainly for the thermal spas find the best conditions in spring or late autumn, when the thermal water stays warm and the crowds thin right out. In our guide when to go to Ischia you'll find the practical comparison designed for those who need to choose their travel dates, month by month.
Frequently asked questions
What is the hottest month in Ischia?
August, with temperatures reaching up to 29°C and the sea at its peak of 26°C.
What is the rainiest month in Ischia?
November, with around 102mm of rain, followed by December (87mm) and October (70mm). June is the driest month, with just 16mm.
When is the sea swimmable in Ischia?
From June to October the sea exceeds 22°C. The warmest period runs from late June to late September, with peaks of 26°C in August.
Is it cold in Ischia in winter?
Not in the way it is in northern Italy: average temperatures stay between 7°C and 14°C even in the coldest months (January and February), rarely dropping below 6-7°C.
What's the sea temperature in Ischia in October?
Around 22°C, still pleasant for swimming in the first part of the month.
Do Ischia's thermal spas work in winter too?
Yes: hotel thermal pools are indoor or heated and stay warm all year, regardless of outdoor temperature or the rainy season.
