As global temperatures continue to rise, the impact of heatwaves (HWs) becomes increasingly striking. The increasing frequency and intensity of these events underscore the critical need to understand regional-scale mechanisms and feedback, exacerbating or mitigating HW magnitude.

Here, we use an ensemble of convection-permitting regional climate models (CPRCMs) to elucidate future HW changes at these fine spatial scales. We explore whether the recently highlighted drier/warmer signal introduced by CPRCMs improves summer temperature extremes representation and if it modulates future HW changes compared to convection-parameterizing regional climate models (RCMs).

In historical runs, CPRCMs show a more realistic representation of summer maximum temperature according to a ground-station-based evaluation.

CPRCMs project substantially drier conditions than RCMs. This is associated with a modulation of HW temperature changes which show diversified spatial patterns, magnitudes, and signs.

CPRCMs ensemble shows an overall reduction in HW metrics future changes inter-model spread compared to the RCMs ensemble.