Mytilus californianus, the California mussel, is a foundation species and dominant space-holder in the rocky intertidal zone, an environment that goes through extreme temperature shifts on a daily basis as organisms are submerged in seawater during high tide and exposed to terrestrial conditions during low tide. Mussels create protein ‘anchors’ called byssal threads that allow them to attach to rocks and each other. Previous work has examined how wave action negatively affects mussel attachment. Yet to date, few studies have addressed the role of temperature during low tide on attachment strength of mussels, despite the clear importance of this topic in the context of the rising temperatures predicted with a changing climate. We used laboratory manipulations to investigate how temperature during low-tide affects three components of mussel attachment: byssal thread production, individual mussel attachment strength, and single byssal thread strength. We collected mussels from two southern California field sites and set up a fully factorial seven-day experiment with two types of treatments: number of low tide exposures (exposure on the first day followed by six days of submersion or exposure each day for seven days) and temperature during low tide exposure (ambient or elevated temperature). In the elevated temperature treatment, we used small heaters to individually raise body temperatures by XoC.We predicted and have found that mussels exposed to natural ambient treatments generally have greater individual mussel attachment strength and single byssal thread strength than mussels exposed to elevated temperatures.