We have acquired two different weather stations in the past few years, the type that transmit information from an outside sensor to an inside display. One, which is LCD and does not show humidity, tells us the outside temperature on one of our balconies is -23C
The second one, however, tells us that the outside temperature on the second balcony is LL.L
I am confident the LL.L means this device has reached its lower limit for temperatures.
Update: Before MA posted his comment and link, I had taken this photo of the specifications of our weather station but had not had time to post the photo:
Indeed the lower limit of the temperature range for the outdoor sensor is -20C. That day, London Ontario set a record low of -26C.