North America has witnessed unprecedented heatwaves and catastrophic wildfires in the past decade, with severe repercussions for humans and ecosystems. These extreme events are strongly influenced by remote processes like the boreal summer intraseasonal oscillation (BSISO), associated with tropical organized convection. Here, we find a robust eastward shift of BSISO convection in a warmer climate, which will induce stronger teleconnection patterns and affect the predictability of downstream extremes. These changes will significantly increase heatwave risks by over 20% and large wildfire potential by more than fourfold across broader areas of North America in the future. Our results highlight the growing challenges in addressing the impacts of heatwaves and wildfires and underscore the need for effective long-term adaptation and mitigation strategies.