Significance Our current understanding of how marine biota are adapted to magnitudes, trends, and temporal patterns of variability in sea-surface temperature has arisen from examining long-term records at key ocean locations. However, floating plankton have a different perception of their habitat because they drift in ocean currents. Here we show that upper ocean microbes can be advected up to 3,500 km in latitude in 500 d, and that their operational temperatures exceed the in situ Eulerian temperature range by up to 10 °C, even in locations with strong seasonality. This result revises the present view of thermal exposure in the upper ocean, and provides a new framework for investigating climate change impacts on planktonic organisms.