A new Home Office report has linked the UK’s balmy start to 2025 to a dramatic rise in the number of small boat crossings when compared to the same period last year.
However, analysis by the Sky News data team shows that there has also been a big rise in crossings on days when the weather has been poor.
A record 11,074 people arrived in small boats before May this year, a rise of almost 50% compared with the same period last year.
According to the Home Office figures, 60 of those days this year were classed as “red days” – where Channel crossings are more likely because of good weather – compared with just 27 last year.
In a new report released today, the Home Office says that the doubling of red days from January to April 2025, compared with the same period in 2024, “coincides with small boat arrivals being 46% higher” over that period.
Our analysis, using similar criteria to the Home Office, but not attempting to directly replicate their methodology, agrees that there have been an unusually high number of days this year when the weather makes for good sailing conditions.
But it also shows that there are significantly more people making the crossing when the weather is not ideal – a rise of 30% on last year, and more than double compared with the year before.
We’ve classified the weather as being favourable on a day when, for several consecutive hours early in the morning, wave height, wind speed, rain and atmospheric pressure were all at levels the Met Office says typically contribute to good conditions for sailing. There’s more detail on our methodology lower down this page.
There is a clear link between better weather and more people arriving in the UK on small boats.
An average of 190 people per day have arrived so far this year when the weather has been fair, compared with 60 on days with less consistently good conditions.
But if we look just at the days when the weather is not so good, we can also see a clear and consistent rise in the numbers over time.
That average of 60 arrivals per “low viability” day is a rise of more than 30% on last year, and more than double the 24 that arrived on each similar day in 2023.
Please use Chrome browser for a more accessible video player
UK sees new Channel migrant record
There are a range of reasons why more people could be crossing on bad weather days.
Smuggler tactics are changing, and Home Office data shows severely overcrowded boats are becoming more common.
In the year to April 2022, just 2% of boats had 60 or more people on board, compared with 47% in the year to April 2025.
In other words, in the space of three years, the number of boats with more than 60 on board has gone from 1 in 50 to every second boat.
Dr Peter Walsh, senior researcher at the Migration Observatory at Oxford University, told Sky News that a rise in demand due to geopolitical issues, like the situation in Afghanistan, may be a factor, but that it is interesting that illegal entries to the EU are down while they have risen in the UK.
What is the Home Office doing?
The current government has placed a major emphasis on disrupting the smuggler gang supply chains to restrict the number of boats and engines making it to the French coast.
Part of the problem is that French authorities are unable to intercept boats once they are already in the water, which is believed to have been exacerbated by good weather.
The Home Secretary, Yvette Cooper, has confirmed the French government is reviewing its policies after she pressed for a law change that would allow police in France to apprehend migrants in shallow waters.
The Home Office released figures on Thursday that revealed France is intercepting fewer Channel migrants than ever before, despite signing a £480m deal with the UK to stop the crossings.
Please use Chrome browser for a more accessible video player
‘Britain has lost control of its borders’
How are we defining good and bad days?
The Home Office says that its assessments of the likelihood of small boat crossings are passed to it by the Met Office.
“A Red, Amber, Green (RAG) daily crossing assessment is produced of the likelihood of small boat crossing activity based on the forecasted wave height and other environmental and non-environmental factors; such as rates of precipitation, surf conditions on beaches, wind speed and direction, open-source forecasts, and recent trends.”
We’ve not tried to replicate that methodology directly. But we’ve looked at Met Office categorisations for wave height, wind speed, atmospheric pressure and rain, four factors that each contribute to fair conditions for sailing in a small boat.
They say a wind speed of 5m/s is a “gentle breeze”. They classify precipitation as at least 0.1mm of rain per hour. If the “significant wave height” – the height of the highest one third of waves – is below 0.5m, they say that’s “smooth”.
Standard pressure at sea level is 1,013hPa, and high pressure “tends to lead to settled weather conditions” . We’ve set the minimum pressure at 1,015hPa, on the high side of standard, and used the thresholds listed above for the other metrics.
We’ve categorised a “high viability” day as one in which all four of those conditions were met in the Dover Strait for at least four consecutive hours, between 2am and 6am UK time.
A “low viability” day is where there is no more than one hour during which all those conditions were met. And “medium” is when the conditions are met for 2-3 hours.
The Data and Forensics team is a multi-skilled unit dedicated to providing transparent journalism from Sky News. We gather, analyse and visualise data to tell data-driven stories. We combine traditional reporting skills with advanced analysis of satellite images, social media and other open source information. Through multimedia storytelling we aim to better explain the world while also showing how our journalism is done.
