Sensors on future satellite platforms will be used routinely for volcano monitoring, with infrared channels offering the potential to detect and measure temperatures of features such as lava bodies and fumarole fields. This is possible even though the surface temperature distributions associated with such phenomena are typically inhomogeneous at the pixel scale, so long as simplifying assumptions can be made. To test the applicability of the technique, we have carried out field studies of a range of volcanic thermal manifestations using portable infrared thermometers. Rock surface temperatures around fumarolic vents exhibit greater stability with time than those associated with actively degassing lava bodies, but in both cases volcanogenic fumes can significantly attenuate the emitted infrared radiation. The scale of the temporal variability, at a given wavelength, dictates the quantitative value of isolated satellite 'snapshots'. If more spectral channels in the infrared were available on remote sensing platforms then more components of the surface temperature distribution could be extracted from the data. Imaging spectrometry offers the greatest flexibility, although data processing, including correction for atmospheric effects, would present difficulties.