How Does Cold Temperature Affect Light Bulbs?

Incandescent bulbs, soon to be a thing of the past, are not impacted by cold temperatures. The light bulbs most typically replacing incandescent bulbs -- compact fluorescent lights (CFLs) -- are impacted by cold temperatures. CFLs are light bulbs that use electricity to excite mercury vapor and produce light. Compact fluorescent light bulbs, though energy-efficient, are negatively affected by cold temperatures.

Cold temperatures reduce the illumination generated by standard compact flourescent light bulbs.


When a compact fluorescent light bulb switches on, current flows through the bulb, heating a cathode, a type of electrical conductor, until it emits electrons. Electrons then collide into noble gas atoms contained in the bulb, ionizing them and generating plasma. The plasma increases the gas's conductivity, enabling the flow of higher levels of current through the bulb.

Decreased Flux

Exposure to cold temperatures makes it difficult for the cathode in the fluorescent bulb to heat properly, increasing the voltage needed while decreasing the bulb's flux, or level of illumination. Standard compact fluorescent bulbs decrease flux by up to 50 percent at 32 degrees Fahrenheit.

Amalgam CFLs

The inclusion of amalgam, a substance formed via the reaction of mercury with another form of metal which controls mercury pressure in the bulb, enables compact fluorescent lights to work under temperatures as low as 1.4 degrees Fahrenheit. Amalgam compact fluorescent bulbs take an average warmup time of 3 minutes to reach full flux.