Organisms increasingly face extreme temperatures due to climate change and may depend upon flexible, behavioral strategies to cope with altered thermal regimes. Burrows and cavities provide animal-engineered microhabitats with more stable and moderate temperature and humidity profiles that can benefit their occupants, and by modifying burrow architecture and use, animals can mitigate their exposure to high temperatures. However, the exact extent to which burrows alter thermal regimes and provide protection against extreme heat events in the wild is often unknown. These questions are key for burrowing species of conservation concern, like the Mojave desert tortoise. Here, we characterize how desert tortoise burrows buffer exposure to surface temperature and humidity regimes using data from natural tortoise burrows in the wild. We then link these results to data from natural and artificial burrows used by nesting females at outdoor enclosures, including data collected during a heat-wave that resulted in complete nest failure. Our results highlight the high buffering potential of burrows, but also suggest that in some cases –particularly for younger life stages–burrows may not be sufficient to protect animals from extreme temperatures that are projected to increase under climate change. These results can inform future head-starting methods for this species.