St Swithin's Day: Could it rain for the next 40 days? Here's what we know

July 15 is St Swithin's day and according to an old legend, it could determine the weather for the rest of the summer

People at Warren Beach in Rosscarbery taking advantage of a sunny day. Picture: Andy Gibson

In the midst of a mostly sunny summer, many of us are still crossing our fingers in the hopes of a grand stretch of fine weather.

According to folklore, today's date — July 15 — is an important one that may determine how the rest of the season will go and whether or not we can expect the summer heatwave we long for. 

What is St Swithin’s Day?

July 15 is St Swithin’s Day. Fans of David Nicholls’ One Day will also know it is the date in which the author returns to the lives of Emma and Dex over the course of 20 years.

St Swithin himself was the Bishop of Winchester from 852 until his death in 863. His feast day in England is July 15.

It is believed that if it rains on St Swithin’s Day, it will rain for the next 40 days and 40 nights  — that is, until the end of the summer. Similarly, if the weather is good, it will remain this way for the same period.

Where does this idea come from?

Legend has it that on July 15, 971, St Swithin's remains were moved to a cathedral. The saint was not happy with this and a storm followed. After that, it rained for 40 days and 40 nights.

A poem states:

"St Swithin's Day, if it does rain

"Full forty days, it will remain St Swithin's Day, if it be fair 

"For forty days, t'will rain no more."

So, what does the weather look like for St Swithin’s Day?

According to Met Éireann, there will be rain on St Swithin’s Day across Ireland.

Their national forecast describes a generally cloudy and wet start to the day with outbreaks of rain and some possibly thundery downpours. 

Drier and brighter weather will extend eastwards to many areas throughout the day, with some scattered showers. Parts of the southwest are likely to stay cloudy with showers for much of the day. Highest temperatures of 16 to 20 degrees in moderate to fresh westerly breezes.

While we can't see the forecast fr the next 40 day, Met Éireann says the rest of the week looks set to be changeable and rather unsettled, with early indications suggesting Sunday will be a bright day with sunny spells and just well-scattered showers.

• This article was first published in July 2024 and updated on July 14, 2025.