This study provides the first monthly resolved, 41‐year record of geochemical variations (δ¹⁸O and Sr/Ca) in a fast‐growing Diploria strigosa brain coral from Guadeloupe, Caribbean Sea. Linear regression yields a significant correlation of coral Sr/Ca (δ¹⁸O) with instrumental sea surface temperature (SST) on both monthly and mean annual scales (e.g., r = −0.59 for correlation between Simple Ocean Data Assimilation (SODA) SST and Sr/Ca, and r = −0.66 for δ¹⁸O; mean annual scale, p < 0.0001). The generated coral Sr/Ca (δ¹⁸O)‐SST calibration equations are consistent with each other and with published equations using other coral species from different regions. Moreover, a high correlation of coral Sr/Ca and δ¹⁸O with local air temperature on a mean annual scale (r = −0.78 for Sr/Ca; r = −0.73 for δ¹⁸O; p < 0.0001) demonstrates the applicability of geochemical proxies measured from Diploria strigosa corals as reliable recorders for interannual temperature variability. Both coral proxies are highly correlated with annual and seasonal mean time series of major SST indices in the northern tropical Atlantic (e.g., r = −0.71 for correlation between the index of North Tropical Atlantic SST anomaly and Sr/Ca, and r = −0.70 for δ¹⁸O; mean annual scale, p < 0.001). Furthermore, the coral proxies capture the impact of the El Niño–Southern Oscillation on the northern tropical Atlantic during boreal spring. Thus fast‐growing Diploria strigosa corals are a promising new archive for the Atlantic Ocean.