The CSU weather station, a few blocks from my house, reported a low temperature of -21.8 °C (-7.3 °F) at 6:20 this morning. It was 11 °C inside my house. The furnace had not started because its humidifier's exhaust tube had a small ice plug. Ruth unblocked it using a hair dryer. We're lucky that this kind of cold only comes around once a year. I'm going to wait until the air temperature gets close to -10 °C before I go running today.