Unexpected weather events and patterns that are considered extremely unusual outliers in the regions where they occur. Unexpected heat waves, such as the 2021 Western North America heat wave that set new record-high temperatures in Canada, or the February 2021 North American cold wave that caused significant damage in the state of Texas, are examples of such events. There is some evidence to suggest that climate change is causing extreme weather events to occur both more frequently as well as more severely.