These plots show the indoor and outdoor temperatures at the LIGO Livingston and LIGO Hanford Observatories as measured by thermometers located at the end of the X-arm (EX), the end of the Y-arm (EY), and the corner station (CS; near the beam splitter, where the X- and Y-arms meet). Any extreme dips in these plots are likely due to gaps in recorded data rather than rapid temperature swings.