Abstract Coral‐based temperature reconstructions and gridded sea‐surface‐temperature (gSST) data sets both provide valuable insights into tropical climate variability. However, coral records often exhibit greater interannual to decadal variability than is observed in gSST products or Earth System Models (ESMs). This discrepancy is often attributed to large differences in spatial scale: coral records reflect conditions over areas of only a few square centimeters, while gSST and ESM grid cells span 1 to 10,000 km 2 . In situ temperature loggers on coral reefs allow us to isolate the effects of spatial scale from other non‐climatic influences on coral temperature records. Many logger studies focus on hourly to monthly timescales, temperature biases, and whether gSST can capture temperature extremes associated with coral bleaching and mortality; however, paleoclimate reconstructions provide an understanding of variability on longer timescales. Here, we compare the power spectral density and coherence of logger temperature and gSST on daily to decadal timescales using logger data from 42 sites on the Great Barrier Reef. We find that temperature variations recorded by loggers on reefs are well correlated with and have the same amplitude as gSST variations at decadal to annual timescales. Therefore, the excess decadal variability commonly seen in coral‐based temperature reconstructions cannot be attributed to a general effect of spatial scale. Plain Language Summary Coral‐based temperature records are used to study past ocean temperatures. However, these records sometimes show more year‐to‐year and decade‐to‐decade variation than gridded temperature data sets from satellite‐ and ship‐based measurements. One possible explanation is that corals measure temperature at a very small local scale, while global data sets average conditions over large areas. To test this idea, we analyzed data from temperature loggers placed at 42 sites across the Great Barrier Reef and compared them to gridded sea‐surface temperature (gSST) data sets. We looked at how well the two matched at timescales from days to decades. Our results show that the variability of reef logger temperatures and gSST is very similar at annual to decadal timescales. This means that the extra variability often seen in coral‐based temperature reconstructions is unlikely to be caused by differences in spatial scale alone. Key Points Gridded sea‐surface‐temperature (gSST) and in situ loggers record similar temperature variations on decadal to monthly timescales Excess variability in coral‐based temperature reconstructions relative to gSST is not due to differences in spatial scale