Every few days a low pressure system rambles across the US, and if it passes close enough to us and is strong enough, we may see some clouds and precipitation, followed by blue skies and cooler temperatures. Such fluctuations are a feature of our Midwest climate. At the global scale, there are also semi-regular disruptions that change the weather, and none is better known than ENSO — the El Niño-Southern Oscillation. We expect ENSO events every 3 to 7 years. When a strong ENSO event occurs, its fingerprints can be seen many places around the globe. If you are a farmer in Australia, Indonesia, South Africa, or northern South America, plan for a dry spell. In the southern third of the US, expect more rain than usual. The global average temperature is always warmer than average during an ENSO. As with passing storm systems, there are some regular features, but also lots of unknowns about how ENSO will affect a given place.
Soil Science Extension
University of Wisconsin Madison