Derry is set for a warm and sunny Thursday as the Maritime Festival gets underway, according to Met Office and Met Éireann forecasts.

Temperatures are expected to climb as high as 27 degrees Celsius with light winds and hazy sunshine. The Met Office said sea breezes may develop along the coast, and there is a small chance of an isolated shower later in the day.

Met Éireann cautioned that thunderstorms could develop in western and northwestern areas by evening, with temperatures ranging from 25 to 31 degrees across the country.

High pollen counts are also predicted for Thursday, posing a risk to hay fever sufferers.

Conditions will turn markedly wetter from Friday, with both agencies forecasting outbreaks of heavy rain and thunderstorms through the weekend.

Friday will see showers or longer spells of rain, possibly thundery, and maximum temperatures will drop to around 19 degrees. Overnight lows will fall to 15 degrees.

Further rain is expected on Saturday, with highs of 22 degrees and overnight lows of 13 degrees. Sunday should bring brighter intervals but scattered showers will persist, with temperatures around 18 degrees and overnight lows of 12 degrees.

The Met Office said the general outlook remains changeable, with a chance of drier weather for many at the start of July, though northwestern areas may still see rain and strong winds at times.