When you are talking about weather on Mercury you are not talking about much. The planet does not have an atmosphere worth mentioning. so when you talk about Mercury you talk about its climate. You look at how its surface temperatures change over time. You also have to mention Mercury’s seasons. Even though we tend to think of seasons as fall, winter, spring, and summer weather, on the cosmic scale it is the times when different parts of a planet is exposed to more or less sunlight.
When we consider temperatures on Mercury we can see that we truly have the better deal on Earth. On Earth we complain if the weather hits 90 to 100 degrees Fahrenheit or it dips below 30 degrees Fahrenheit. However Mercury experiences much more extreme changes in temperature. First off the planet is much closer to the sun. This is because of the planet’s positions and also because of it more elliptical orbit which makes it pass even closer to the sun at certain points. The second factor is that Mercury’s atmosphere is so thin that is can not retain solar radiation like Earth can.
The result of these two conditions on Mercury are very extreme temperature changes. During the Day mercury gets up to 10 ten times more solar energy than Earth. So temperatures can go as high 430 degrees Celsius. That is 806 degrees Fahrenheit. If a human being was to be exposed to such high temperatures they would burst into flames and burn to a crisp. In fact it is so hot that lead and zinc would met. During the night Mercury can’t retain heat so its temperature plummets to a freezing -183 degrees Celsius or -297.4 degrees Fahrenheit.
When it comes to seasons Mercury is tilted away from the sun so its southern hemisphere gets hotter summers and cooler winters. The orbit also effects the intensity. Since the northern hemisphere tends to tilt towards the sun on the longer end of Mercury’s orbit so its winter and summers are not as intense.
We’ve also recorded an entire episode of Astronomy Cast all about Mercury. Listen here, Episode 49: Mercury.