A candle works because of the burning of wax, with the supply of oxygen from the air. Set fire to the wick, which is the start of the burning process of a candle. The heat from the fire will melt and vaporize the wax below. The vaporized wax will be the adding fuel to the fire and make sure the candle keep burning, until the wax is running out (of course, we need air all the time).

So will the candle burn longer in hotter air? Cold and hot is a relative concept. Hot as sun will immediately burn the whole candle in seconds; while in the coldest places you may even have trouble setting the fire to the wick, let alone the burning of the candle. From those two extremes, you can immediately see that hotter air will probably make the candle burn shorter. But this is not exactly what you are asking. Let's compare the hot air (say 80 degrees Fahrenheit) in the summer and cold air ( say 40 degrees Fahrenheit) in the winter. Will they make some differences? The hotter air will speed up a few processes that will make the burning faster. For example, the supply of oxygen, and the heat conduction necessary to melt and vaporize the wax. But there is one crucial thing to remember, the temperature of the flames are much higher than the air temperatures. The brightest part of the flame has a temperature of about 2200 degrees Fahrenheit (the top of the flame), and the hottest part of the flame is about 2500 degrees Fahrenheit (the blue or white edge of the flame in the very bottom, and this part plays the major role of melting and vaporizing the wax). In this sense, the hot or cold air will not matter that much, because the heat from the bottom flame is the dominating factor that determines the burning time of the candle. So to summarize, whether in hot air or cold air, the candle will burn probably the same amount of the time.

Although, the hotter air will in principle make the burning process faster, but it doesn't play a dominating role. The difference is minimum (unless otherwise under extreme conditions).

Candles work by burning wax. The solid wax that makes up the body of the candle is melted by the heat of the flame, then is absorbed into the wick where it is burned. If the air (and therefore the solid candle wax) is cold, then more of the energy from burning must go toward heating the solid wax before it is melted. This means less of the candle will melt for a given unit of energy and the candle will burn more slowly. That being said, the flame is at a much higher temperature than the air is likely to be, so the effect will not be dramatic.

That's a fun question. What do you think? I think candles would burn a tiny bit longer in cold air, because there'd be a tiny bit less heat around the candle and the flame.

Candles in windy or still air is another fun thing to picture in your mind.

Thanks for the great question!

When you light a candle, you heat up the wax that surrounds the wick, or the string that runs through the candle. When the wax gets hot enough, the wick catches fire. As the wick burns, it heats the wax under it and that keeps the wick lit.

Should the candle be cold, let’s say because the air is cold, it will take a little longer to heat up the wax to get the wick burning. So candles do burn longer when cold, and candles are colder when in cold air.

However, the air temperature may not change the temperature of the wax all that much. Some people will even put their candles in the fridge to get the wax even colder, and to get the flame burning even longer.