A senior researcher at the University of Oxford has said there is “no evidence” to suggest weather is the main reason for more migrants crossing the Channel.
Some 11,074 migrants arrived in the UK between January 1 and April 30 after crossing the English Channel.
There were 60 so-called “red” days during this period, which means factors such as wind speed, wave height and the likelihood of rain meant crossings were classed by officials as “likely” or “highly likely”.
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By contrast, there were 27 red days in the same period last year, less than half the number in 2025, with 7,567 arrivals recorded – nearly a third lower than the total for this year.
Dr Peter Walsh, senior researcher at the Migration Observatory at the University of Oxford, said while it is clear weather has an important impact on crossings in the short-term, there is “no evidence” to suggest weather is a major factor explaining the long-term increase of arrivals seen over the past eight months.
He added: “Other factors, such as the number of people wanting to reach the UK and the number and professionalisation of smuggling gangs are likely to be more important.”
Assessments of the likelihood of migrant crossings are prepared for the Home Office by the Met Office.
Red days mean the probability of migrant activity in the Channel is greater than 55 per cent with crossings classed as “likely” or “highly likely”.
Green days are determined by the likelihood being less than 35 per cent, with crossings “unlikely” or “highly unlikely”.
The analysis is based on data recorded in the Dover Strait and does not consider wider factors such as the availability of dinghies.
Meanwhile, 1,195 migrants made the journey to the UK in 19 boats on Saturday, in the highest daily total recorded so far this year.
The cumulative total for the year, 14,812, is the highest for the first five months of a year since data collection began in 2018.
The Prime Minister Sir Keir Starmer's official spokesman acknowledged there were “no quick fixes” to the problem of tackling migrant crossings.
A Home Office spokesman said the government has stopped 9,000 crossings from France this year and that it is “restoring grip” to the broken system.
“This is a weak Government, with no plan to end illegal immigrants crossing the Channel.
“Blaming the weather for the highest ever crossing numbers so far this year is the border security equivalent of a lazy student claiming ‘the dog ate my homework’.”
