Results from an analysis of the Southampton Oceanography Centre (SOC) global air–sea heat flux climatology, which has been calculated using in situ weather reports from voluntary observing ships covering the period 1980–93, are presented. Systematic errors in the fluxes arising from differences in observing procedure have been quantified and corrected; the magnitude of these errors is up to 15 W m−2 with strong seasonal and regional variations. Despite these corrections, closure of the ocean heat budget is not obtained as the global mean net heat flux is an oceanic gain of 30 W m−2. The validity of closing the heat budget by global scaling of the flux components is assessed by comparison of the SOC flux fields with Woods Hole Oceanographic Institute research buoy measurements. The level of agreement between the two is found to vary from one site to another. Thus, closure of the ocean heat budget requires regional adjustments to the flux components in order to avoid significant biases in the adjus... Abstract Results from an analysis of the Southampton Oceanography Centre (SOC) global air–sea heat flux climatology, which has been calculated using in situ weather reports from voluntary observing ships covering the period 1980–93, are presented. Systematic errors in the fluxes arising from differences in observing procedure have been quantified and corrected; the magnitude of these errors is up to 15 W m−2 with strong seasonal and regional variations. Despite these corrections, closure of the ocean heat budget is not obtained as the global mean net heat flux is an oceanic gain of 30 W m−2. The validity of closing the heat budget by global scaling of the flux components is assessed by comparison of the SOC flux fields with Woods Hole Oceanographic Institute research buoy measurements. The level of agreement between the two is found to vary from one site to another. Thus, closure of the ocean heat budget requires regional adjustments to the flux components in order to avoid significant biases in the adjus...