This talk was given at the 25th International SST Users’ Symposium and GHRSST Science Team Meeting (GHRSST25) held in Montreal, Canada/Online from 10 – 14 June 2024. Explore the full program at GHRSST25 on the GHRSST Website here. Abstract Ocean temperature variations off the coast of Nova Scotia are quantified through analyses of data from in situ and satellite remote sensing observations, and high-resolution numerical ocean models. The analyses reveal significant variations at various time-space scales, including: 1) rapid cooling in nearshore waters associated with extreme cold-air outbreaks; 2) frequent cold spells at seabed along the coast from late fall to early spring; 3) large-scale cooling or warming spanning over a season or longer; 3) extensive upwelling along the coast from late-spring to fall; 4) space-time (seasonal and interannual) variations of marine heat waves and cold spells at surface and in the water column; and 5) interannual variations of upwelling along the coast. The forcing mechanisms and predictability of these variations are explored through analysis of atmospheric forcing and ocean model solutions. The potential relevance to applications in marine ecosystems and fishery is discussed.