We present a new grid of LTE model atmospheres for weakly magnetic (B < 10 10 G) neutron stars, using opacity and equation of state data from the OPAL project and employing a fully frequency- and angle-dependent radiation transfer. We discuss the dierences from earlier models, including a comparison with a detailed NLTE calculation. We suggest heating of the outer layers of the neutron star atmosphere as an explanation for the featureless X-ray spectra of RX J1856.5{3754 and RX J0720.4{3125 recently observed with Chandra and XMM.