Thunder, indicated by the fall of the mercury in sultry weather.
Cold, indicated by the rise of the mercury in spring, autumn, and winter.
Heat, by the fall of the mercury in summer and autumn.
Frost, indicated by the rise of the mercury in winter.
Thaw, by the fall of the mercury during a frost.
Continued bad weather, when the fall of the mercury has been gradual through several fine days.
Continued fine weather, when the rise of the mercury has been gradual through several foul days.
Bad weather of short duration, when it sets in quickly.
Fine weather of short duration, when it sets in quickly.
Changeable weather, when an extreme change has suddenly set in.