weather-lights

from The Century Dictionary.

• The auroral light, so called because supposed by some to be indicative of approaching dry weather, or the result of preceding clear, cool weather. The term is also applied to the very distant flashes of light known as ‘heat-lightning’ or ‘sheet-lightning,’ which often follow a hot summer day and are supposed to be due to the heat, although they are generally due to the existence of thunder-storms in the distance.