Record-breaking extreme wildfires have occurred frequently around the globe in recent years, causing severe loss of life and property and sounding the alarm for climate and ecological changes. Wildfires are a type of compound extreme events, often with a combination of high temperatures, low relative humidity, strong winds, and droughts. Why have extreme wildfires occurred frequently in recent years? What is the possible connection with climate change? This article covers three topics: the meteorological conditions for wildfires, long-term changes of wildfires and their climatic causes, and the impacts of wildfires on climate and ecosystems. There is strong feedback between climate change and wildfires. On one hand, the wildfire risk is increasing with high temperatures and droughts under climate change. On the other hand, extreme wildfires can produce large amounts of greenhouse gas and aerosol emissions, as well as affect ecosystems, which can further feedback to regional and global climate. The complex feedbacks pose challenges for adaptation to climate and environmental changes.