## What is the difference between weather and climate?

People often ask, "What is the difference between climate and weather?" Although climate and weather are closely related, there are some important differences. The simple explanation is weather is what you get today and climate is what you get over the long-term.

An analogy may help to explain. Most of us have heard of the famous baseball player Babe Ruth. He hit a high percentage of home runs over his career. But when he stepped up to the batter’s box in a game, you didn’t know if he would hit a home run or strike out (which he was also famous for). What happens at that individual "at bat" is weather. The statistics of home runs and strikeouts over his career are climate.

If you don’t remember Babe Ruth, here is another example. Imagine a woman walking her dog on the beach. As they pass by, you can see their tracks in the sand. The woman’s tracks are in a straight line. But the dog’s tracks may show an erratic pattern. Depending on the length of the dog’s leash, the dog’s tracks show a pattern of darting back and forth over the woman’s track as it investigates various spots on the beach. The dog's tracks are weather and the woman’s tracks are climate

How can the planet be warming considering the cold spells we sometimes experience in the US? The US only makes up 2% of the Earth’s surface and only 7% of the Earth’s land area. The temperature over the rest of the world can easily more than offset the temperature in the US. During a US cold snap, temperatures in much of the rest of the Earth may be above average.

The climate can be tipped in a different direction, often by relatively small external influences. Returning to Babe Ruth, a bit of arthritis in an elbow or a small change in eyesight could greatly impact his batting average.
You may ask, "If scientists have difficulty predicting tomorrow’s weather, how can they predict climate far in the future?" Weather is short-term and chaotic, and is determined by current atmospheric systems that may soon be replaced by other systems, so it is difficult to predict weather more than a few days in advance.

Conversely, climate is the average weather over a long period of time, typically 30 years or more. It is determined by large-scale forces like the level of greenhouse gases in the atmosphere, so it is easier to predict long-term changes in climate than short-term changes in weather.

A listing of USDA and university websites focused on weather and climate can be found on the Ag Decision Maker Outlook page.

Don Hofstrand, retired extension agricultural business specialist, agdm@iastate.edu
Reviewed by Dr. Eugene Takle, retired professor emeritus Iowa State University