Here, we present an annually-resolved record of summer flood frequency from the varved (annually laminated) sediments of proglacial Lake Oeschinen (46 30 N-7 44 E, 1580 m, NW Swiss Alps) back to AD 884. This dataset is produced based on the occurrence of flood event layers in the sediments. The chronology of the sediment record is based on multiple varve counts and validated with historical floods chronicled in written documents (back to the 14th century), 210Pb, 137Cs and 14C AMS dates.Our record of flood frequency suggests more frequent floods under cool and humid climate during the warm seasons. This picture is consistent with other studies from small and medium size catchments at mid- and high elevations in the Alpine area. However, the 13th century reveals a period with high flood frequency during warm and moderately dry (average precipitation) conditions. This anomalous situation is currently not understood; nonetheless, this is also one out of several possible scenarios for the future. From the different combinations found in our record, we conclude that the relation between floods, precipitation and temperature and, in consequence, future projections remain poorly constrained.