Official Statistics

Small boat arrivals and the impact of crossing conditions

Published 3 June 2025

This note has been produced to provide an overview of the impact of crossing conditions on small boat arrivals across the English Channel.

Small boat arrival numbers are subject to seasonal fluctuations in part due to changes in the weather, typically with peaks in warmer summer months when crossing conditions are more favourable. Just as small boat arrivals are subject to seasonal variation through any given year, there is also variation in arrivals across years.

Assessments of the likelihood of small boat crossings are passed to the Home Office 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.

If the probability of small boat activity is greater than 55%, crossing activity is assessed as ‘likely’ or ‘highly likely’ (a ‘red day’). If the probability of small boat activity is less than 35%, then activity is assessed as ‘unlikely’ or ‘highly unlikely’ (a ‘green day’). This is based on data recorded in the Dover Strait. This scale does not consider other factors which influence arrival numbers such as availability of vessels.

See the ‘For users of these statistics’ section for more details on how RAG days are determined.

1. Total UK arrivals versus red days

Figure 1: Number of small boat arrivals and number of red days per month, May 2021 to April 2025

Source: Small boat arrivals and crossing days: data tables – SB_01

Figure 1 shows that monthly arrivals follow a seasonal cycle with arrivals tending to peak around late summer and fall during the winter months. On average 65% of small boat arrivals occur in the latter part of the year between July to December. This coincides with 49% of red days occurring in the latter half of the year (although in calendar year 2024, 57% of red days occurred between July to December).

Table 1 shows an increase in red days in October to December 2024 (42) compared to the same period in 2021 to 2023 (an average of 14). This was accompanied by a high number of arrivals (11,572), whereas the same period in 2021 to 2023 was associated lower number of arrivals (an average of 9,492 arrivals).

Table 1: Number of red days and total arrivals from May 2021 to April 2025

Month	Number of red days				Total number of arrivals
	YE April 2022	YE April 2023	YE April 2024	YE April 2025	YE April 2022	YE April 2023	YE April 2024	YE April 2025
May	6	16	13	21	1,627	2,916	1,664	2,881
Jun	18	11	16	20	2,177	3,140	3,823	3,041
Jul	14	12	10	18	3,512	3,687	3,299	3,414
Aug	7	16	14	16	3,053	8,631	5,369	4,149
Sep	14	13	15	13	4,602	7,964	4,729	4,192
Oct	4	6	6	19	2,701	6,900	1,869	5,417
Nov	11	4	3	13	6,971	4,082	1,661	2,901
Dec	6	1	2	10	1,770	1,744	1,077	3,254
Jan	9	4	5	17	1,339	1,180	1,335	1,098
Feb	0	10	5	8	143	1,773	920	958
Mar	11	3	9	19	3,066	840	3,180	4,586
Apr	7	6	8	16	2,143	2,153	2,132	4,432
Total	107	102	106	190	33,104	45,010	31,058	40,323

Source: Small boat arrivals and crossing days: data tables – SB_01

The year ending April 2025 had a greater number of red days (190) compared to the previous year (106), and 81% more red days than the average number of days in the years ending April 2022 to 2024. Additionally, January to April 2025 had more than double the number of red days (60) compared to the same period in 2024 (27). This coincides with small boat arrivals being 46% higher in January to April 2025 with 11,074 people arriving to the UK by small boat, compared to 7,567 arrivals during these months in 2024.

Figure 2: Total small boat arrivals per type of day per month, May 2021 to April 2025

Source: Small boat arrivals and crossing days: data tables – SB_01

As Figure 2 illustrates, the vast majority of small boat arrivals occur on a red day, with red days accounting for 35% of all days and 84% of total arrivals between May 2021 to April 2025. A further 11% of arrivals occurred on amber days and 5% of arrivals on green days.

Between May 2021 and April 2023, there were 15 days of over 800 arrivals, accounting for 20% of all arrivals in this period. This has decreased since May 2023, with 4 days of over 800 arrivals, accounting for 5% of all arrivals between May 2023 and April 2025. This coincides with a reduction in the concentration of arrivals into single months, as shown by Figure 2.

Figure 3: Number of small boat arrivals and number of red days per year, May 2021 to April 2025

Source: Small boat arrivals and crossing days: data tables – SB_01

Figure 3 (above) shows how total UK arrivals by small boat compares to the number of red days annually since 2021.

2. Number of people per small boat

Table 2: Number of small boats arriving in the UK by the number of people per boat from May 2021 to April 2025¹

Year ending	1 to 50 people	50 to 59 people	60 to 69 people	70 to 79 people	80+ people	Total number of boats
April 2022	1,042	50	13	3	8	1,116
April 2023	710	278	50	6	1	1,045
April 2024	241	209	118	35	11	614
April 2025	225	168	189	123	33	738

Notes:

1. Events that have not been reconciled between the Home Office and outside agencies have not been included.

Source: Small boat arrivals and crossing days: data tables – SB_02

According to statistics reported in ‘How many people come to the UK irregularly’ in the Immigration system statistics quarterly release, the average number of people per boat has increased in each year, rising to 54 people per boat in the year ending March 2025, compared with 50 people per boat in the previous year and 29 in the same period ending March 2022.

Table 2 shows 738 small boats arrived in the UK in the year ending April 2025, up from 614 in the previous year. Although small boat events have decreased since the year ending April 2022, the number of people per boat has increased. Events with over 70 people per boat increased from 18 between May 2021 to April 2023 to 202 in the following 2 years.

3. For users of these statistics

See the latest press statement on small boat crossings.

Daily small boat arrival numbers from 1 January 2018 are published in Small boat arrivals: last 7 days - GOV.UK. These statistics are taken from provisional operational data and the most recent months figures are subject to change. The small boat arrivals figures may differ from figures published in the final official statistics on Immigration system statistics under the topic “How many people come to the UK irregularly”, which will have undergone a more thorough quality assurance process.

The quarterly Immigration system statistics release presents final and authoritative statistics on small boat arrivals.

3.1 Small boats

A ‘small boat’ is one of a number of vessels used by individuals who cross the English Channel, with the aim of gaining entry to the UK without a visa or permission to enter – either directly by landing in the UK or having been intercepted at sea by the authorities and brought ashore. Small vessels detected making these types of crossings can include, but are not limited to, non-commercially produced inflatable boat, dinghies and kayaks.

The data on arrivals includes individuals who:

• are detected on arrival in the UK
• are detected in the Channel by UK authorities and subsequently brought to the UK

The data on arrivals does not include individuals who:

• arrive in the UK on larger vessels, such as go-fast craft, yachts (except those arriving in the area of operations of small boats), motor cruisers, tugs and fishing vessels - although these are rarely used by irregular migrants at present
• arrive in the UK clandestinely on larger vessels not referenced above, including where hidden in a vehicle on a ferry
• are prevented from departing France, or those intercepted by French authorities and returned to France
• arrive in the UK undetected, or where there have been reports of people making the crossing, but no actual encounters

3.2 RAG days

The Met Office provides a daily assessment of how likely small boat crossing attempts might be in the English Channel (specifically the Dover Strait). This assessment is based on predictive analysis looking at recent trends in crossing attempts and applying this to the coming 10 days. Sea conditions are used as an indicator with other environmental and non-environmental factors then taken into account, such as rates of precipitation, surf conditions on beaches, wind speed and direction, open-source forecasts, and recent trends.

The foundation analysis was initially conducted in 2019. This is frequently revisited, reviewed and refined. The underlying assessments are therefore not static, with baselines constantly evolving to reflect sustained shifts in behaviour. In April 2023, for instance, baselines were updated to reflect a sustained increase in observed crossing behaviour. Due to the high number of factors taken into consideration, no singular factor will directly correlate to the number of red days over an extended period of time (see Figure 4).

Figure 4: Number of red days compared to the number of days with significant wave heights of less than 0.5 metres, May 2021 to April 2025

Source: Small boat arrivals and crossing days: data tables – SB_01; the Met Office

However, whilst the assessments that inform the RAG ratings may change over time, the definition of RAG days have remained consistent. The definitions for the likelihood categories (highly likely, likely, realistic possibility, unlikely and highly unlikely) are defined by the PHIA yardstick (Figure 5). Red days are considered days with a greater than 55% chance of crossings. Amber days are considered days with a 35 to 55% chance of crossings. Green days are considered days with a less than 35% chance of crossings. The expected volume of crossings is not covered by the RAG day analysis. Only the likelihood that at least one small boat crossing is attempted is considered.

Figure 5: PHIA probability yardstick as it appears in the small boats crossing assessments. This describes the probability of an event occurring

Source: Home Office