Good weather and the willingness of people smugglers to cram more people onto small boats have been highlighted by the government as factors driving the level of migrant Channel crossings.
The Home Office has released figures showing that the number of "red days" – when conditions are considered favourable for small boat crossings – peaked in 2024-25.
The figures also show a rise in "severely overcrowded boats" in the same period.
The Conservatives and Reform have accused the government of "blaming the weather" for the record crossings so far this year. The government has said it is working to fix "a broken asylum system" left by the Tories.
Rising numbers
The Home Office figures reveal there were 190 red days in the 12 months to April 2025 – an 80% increase on the previous year and the highest number since records began.
Red days are defined as days which the Met Office has assessed as "likely" or "highly likely" to see small boat crossings, based on things like the height of waves, wind speed and rainfall.
By publishing the red day figures, the first official release of this kind, the government is suggesting a link between good weather conditions and the level of migrant crossings.
So far this year, 14,812 people have arrived in small boats – up about 40% on the same period last year. Almost 1,200 people arrived on Saturday alone.
BBC Verify asked Peter Walsh from the Migration Observatory, based at the University of Oxford, exactly what impact the weather has on Channel crossings.
He said it was a factor but other issues, such as the effectiveness of smuggling gangs and the number of people wanting to reach the UK are likely to be more important.
"A migrant's decision to come to the UK by small boat is important and life-changing for them: will they casually drop their plans and decide not to migrate because of a few consecutive days of bad weather? Or will they just wait until the next safe-weather day," he told BBC Verify.
While acknowledging that gangs have exploited periods of good weather to increase crossings, a Home Office spokesperson insisted the government is "restoring grip to the broken asylum system it inherited".
"That's why we are giving counter-terror style powers to law enforcement, launching an unprecedented international crackdown on immigration crime and have prevented 9,000 crossings from the French coastline this year alone", the spokesperson said.
