The dimensions of Pyrenean glaciers at the time of the Last Glacial Maximum (LGM) interval (29–19 ka) are well established in the eastern part of the range, where 10Be and 36Cl exposure ages have been obtained from boulders embedded in moraines and from ice-scoured rock steps protruding from valley floors. By contrast, glacier dimensions at the time of the LGM among the westernmost valleys remain imprecisely defined because age constraints are mainly provided by glaciolacustrine deposits. Available 14C-based chronostratigraphies from these outwash environments document the time when the glaciers had become sufficiently remote from the proglacial lakes to cease supplying them with sediment-loaded meltwater, but not their exact positions in the same way as moraines would. Overall, the regional age pattern nonetheless suggests the existence, during the LGM, of a climatic gradient along the strike of the range between the Atlantic and Mediterranean, that is, between the two marine sources of potential moisture and heat. Currently available ages suggest contrasting glacial chronologies in response to climate change between east and west: glaciers closest to the Mediterranean readvanced proportionally further during the LGM than glaciers closer to the Atlantic. This scenario has implications for understanding LGM atmospheric circulation patterns and requires further testing.