In mid-February, a high pressure system over central Europe changed the prevailing winds from westerly to southerly, with the latter originating from North Africa. The most noticeable effect were unseasonal high temperatures, with several areas in Britain reaching 20 Degrees C or above. The southerly winds also encouraged an early arrival of Swallow, Sand and House Martins.
With the airflow initially centred on the western side of Britain, it was unsurprising that the first reports came from Cornwall and Wales, as well as Ireland. Surprisingly, up to four House Martins were seen as far north as Shetland. With the continuing good weather in late February and early March, Sand Martins were reported many counties in Britain, typically at wetland sites. The reporting rate for Sand Martin reached almost 1% in the last week, but will likely peak at 15% of complete lists once the majority of the population returns later in spring.