Weather Folklore
St Swithin's Day: The Rhyme, the Saint and What the Data Says
St Swithin's Day falls on 15 July. An old English rhyme says that if it rains that day, it will rain for 40 days, and if it is fair, 40 dry days will follow. It doesn't hold: in daily ERA5 data for London, the Cotswolds and Edinburgh from 2015 to 2024, no year came close to 40 wet or 40 dry days.
By the Weather Witch team · Updated October 4, 2026 · 6 min read
Key facts
- St Swithin's Day is 15 July, the anniversary of the day in 971 when Swithun's remains were moved into the cathedral at Winchester.
- Swithun was Bishop of Winchester from 852 until his death on 2 July 863.
- The Met Office has said there has never been a run of 40 dry or 40 wet days after St Swithin's Day since its records began in 1861.
- In daily ERA5 data for 2015 to 2024, the longest wet streak after 15 July was 18 days (Cotswolds, 2017) and the longest dry streak was 18 days (London, 2022).
- France has a similar weather saint, St Médard on 8 June, and Germany has Siebenschläfertag on 27 June.
St Swithin's Day is 15 July, and according to an old English rhyme, the weather on that day decides the next six weeks: rain on St Swithin's Day means 40 days of rain, and a dry St Swithin's Day means 40 dry days. It is one of Britain's best-loved pieces of weather lore, and it is not true. The Met Office has said there has never been a run of 40 wet or 40 dry days after 15 July since its records began in 1861, and our own check of ten years of daily data for London, the Cotswolds and Edinburgh found nothing close.
Below: the rhyme, the real Swithun, our data check, what it means for a July wedding in the UK, and the saint's cousins across Europe.
What is the St Swithin's Day rhyme?
The St Swithin's Day rhyme is a four-line weather proverb that has been repeated in England for centuries. The version quoted in the Wikipedia article on Swithun runs:
St Swithun's day if thou dost rain For forty days it will remain St Swithun's day if thou be fair For forty days 'twill rain nae mare
You will see both spellings, Swithin and Swithun. Swithun is closer to the Old English name and is the form Winchester Cathedral uses; Swithin is the everyday English spelling.
Who was St Swithin?
St Swithin, or Swithun, was an Anglo-Saxon churchman who served as Bishop of Winchester from 852 until his death on 2 July 863. Little is known for certain about his life. The weather connection comes from what happened a century after he died.
The legend of 15 July 971
According to tradition, Swithun asked to be buried outside the Old Minster at Winchester, where the rain and the feet of passers-by would fall on his grave. On 15 July 971, his remains were moved into the cathedral by Bishop Æthelwold, and contemporary writers recorded many miracles around the move.
The rain story is later. The legend says the saint, unhappy at being moved indoors, sent a storm that lasted 40 days. Historians point out that this version cannot be traced back further than the 17th or 18th century. One 19th-century suggestion was that the proverb grew from a notably wet St Swithin's Day in 1315, but nobody knows for sure.
Does it really rain for 40 days after St Swithin's Day?
No. Rain on St Swithin's Day is not followed by 40 days of rain, and a dry St Swithin's Day is not followed by 40 dry days. British summer weather simply changes too often: a typical July or August brings a mix of fronts, showers and settled spells.
Our data check: 2015 to 2024
To test the rhyme, we pulled daily precipitation from the Open-Meteo historical archive (ERA5 reanalysis) for three of our UK wedding destinations and looked at 15 July and the 40 days that followed, every year from 2015 to 2024. We counted a day as wet if it had at least 1 mm of rain, the same threshold our rain odds tool uses.
| Year | London: 15 July | London: wet days in next 40 | Cotswolds: 15 July | Cotswolds: wet days in next 40 |
|---|---|---|---|---|
| 2015 | Wet | 16 | Dry | 14 |
| 2016 | Dry | 10 | Dry | 10 |
| 2017 | Wet | 19 | Wet | 27 |
| 2018 | Dry | 14 | Dry | 16 |
| 2019 | Dry | 14 | Dry | 18 |
| 2020 | Dry | 10 | Dry | 15 |
| 2021 | Dry | 16 | Dry | 18 |
| 2022 | Dry | 7 | Dry | 13 |
| 2023 | Wet | 13 | Wet | 25 |
| 2024 | Wet | 9 | Wet | 16 |
What the numbers show:
- The rhyme never came true. Across 30 place-years (including Edinburgh), there was never a run of 40 wet days or 40 dry days. The longest wet streak was 18 days (Cotswolds, 2017), and the longest dry streak was 18 days (London, 2022).
- A wet 15 July was not a reliable signal. In London, wet St Swithin's Days were followed by an average of about 14 wet days out of 40, compared with about 12 after dry ones. In 2024, London was wet on 15 July and then had one of the driest late summers in the sample, with only 9 wet days.
- There is a weak tendency in the Cotswolds, where the three wet St Swithin's Days were followed by more wet days on average than the dry ones. With only three cases, that is a coincidence of small numbers, not a law. In Edinburgh the pattern ran the other way.
- Wet summers do happen. 2017 in the Cotswolds had 27 wet days out of 40. That is the sort of summer that keeps the legend alive, but even then dry days broke up the rain.
Ten years is a small sample, so treat this as a fun check rather than a scientific study. It fits what the Met Office has found over more than 150 years: the 40-day rule has never literally come true.
Should you avoid a July wedding in the UK?
A July wedding in the UK is a good bet for warmth and long evenings, but you should plan for some rain whatever St Swithin does. In our ERA5 data for 2015 to 2024, the share of July days with at least 1 mm of rain was:
| Destination | July days with rain | Average July high |
|---|---|---|
| London | 35% | 22.6°C |
| Cotswolds | 42% | 20.6°C |
| Edinburgh | 54% | 18.2°C |
In other words, roughly one July day in three is wet in London and about one in two in Edinburgh. Across the UK as a whole, spring months such as April and May are usually drier, while summer brings warmth. Our guide to the best month to get married compares the trade-offs, and our free wedding rain odds tool shows the historical chance of rain for your exact date and venue.
If your date lands on or near 15 July and a relative mentions St Swithin, you now have the data to smile and move on. If the forecast does turn wet, our guide to rain on your wedding day covers both the folklore (it is meant to be lucky) and the practical plan.
St Swithin's cousins: weather saints across Europe
St Swithin is not alone. Many European countries have a summer saint's day with the same "40 days" or "seven weeks" promise:
| Saint or day | Date | Country | The saying |
|---|---|---|---|
| St Médard | 8 June | France | Rain on St Médard's Day brings 40 days of rain, unless St Barnabas (11 June) fixes it |
| Siebenschläfertag (Seven Sleepers' Day) | 27 June | Germany | The weather on this day sets the weather for the next seven weeks |
| St Godelieve | 6 July | Flanders | A similar rain saying for early July |
| St Swithin | 15 July | England and Scotland | Rain on 15 July brings 40 days of rain |
Our guide to weather superstitions for weddings covers St Médard and other folk charms, and our page of prayers for good weather includes the saints traditionally asked for clear skies.
Keeping the legend, losing the worry
We like St Swithin. His wish to lie under the open sky, rain and all, is rather lovely, and a saint's day rhyme is a far gentler way to talk about weather than a refreshing forecast app. If you want a ritual of your own for a summer wedding, our personal wedding weather ritual is performed for your date and place in the nights before the day, with photo proof and a written blessing. It cannot control the weather any more than St Swithin can, and we say so plainly; it is a way to hand over the worry.
The bottom line
St Swithin's Day is 15 July, the anniversary of the day in 971 when Bishop Swithun's remains were moved into Winchester's cathedral. The rhyme says rain that day brings 40 days of rain, but it has never come true in the Met Office's records since 1861, and in our 2015 to 2024 data check for London, the Cotswolds and Edinburgh, no wet or dry run lasted longer than 18 days. Enjoy the legend, check the real odds for your date, and plan your summer wedding for a British July: mostly warm, sometimes wet, never 40 days of anything.
Frequently asked questions
When is St Swithin's Day?
St Swithin's Day is on 15 July every year. It marks the anniversary of the day in 971 when the remains of Swithun, a ninth-century Bishop of Winchester, were moved from his grave outside the Old Minster into the cathedral building. His feast is also kept on 2 July, the date of his death in 863.
What is the St Swithin's Day rhyme?
The best-known version is: St Swithin's day if thou dost rain, for forty days it will remain; St Swithin's day if thou be fair, for forty days 'twill rain nae mare. In plain English: rain on 15 July means 40 days of rain, and a dry 15 July means 40 dry days.
Is the St Swithin's Day legend true?
No. The Met Office has said that since its records began in 1861, there has never been a run of 40 wet or 40 dry days after St Swithin's Day. Our own check of 2015 to 2024 daily data for London, the Cotswolds and Edinburgh found no wet or dry streak longer than 18 days in the 40 days after 15 July.
Why is St Swithin linked to rain?
Legend says Swithun asked to be buried outside, where rain and passers-by would fall on his grave, and that when monks moved his body indoors on 15 July 971, he sent a great storm in protest. Historians note that this storm story cannot be traced earlier than about the 17th century, long after the event.
Is July a good month for a wedding in the UK?
July is one of the warmest UK months, but not the driest. In our 2015 to 2024 ERA5 data, July had at least 1 mm of rain on 35 percent of days in London, 42 percent in the Cotswolds and 54 percent in Edinburgh. April and May are typically drier across the UK, while summer gives warmth and long evenings.