Time–space synesthetes report that they experience the months of the year as having a spatial layout. In Study 1, we characterize the phenomenology of calendar sequences produced by synesthetes and non-synesthetes, and show a conservative estimate of time–space synesthesia at 2.2% of the population. We demonstrate that synesthetes most commonly experience the months in a circular path, while non-synesthetes default to linear rows or rectangles. Study 2 compared synesthetes’ and non-synesthetes’ ability to memorize a novel spatial calendar, and revealed better (...) performance in synesthetes. The capacity to learn mappings between arbitrary spatial forms and temporal sequences is present in all individuals, and time–space synesthetes’ enhanced visuo-spatial memory abilities may underlie their creation of idiosyncratic spatial calendar forms. (shrink)