Time-series trends in thermal Advanced Very High Resolution Radiometer (AVHRR) data from 1993 to 1998 provide insight into the active volcanic processes at Bezymianny and Kliuchevskoi, two of the most dangerous volcanoes on the Kamchatka Peninsula. The AVHRR time series show differences in these volcanoes' pre- and postexplosive trends: Bezymianny exhibited a thermal precursory signal in all recorded explosions between 1993 and 1998, as well as continued postexplosive activity, and Kliuchevskoi showed only short-lived thermal activity and exhibited precursors before the 1994 paroxysmal explosion. These contrasting characteristics reflect different magma types and eruption styles. At Bezymianny, a persistent thermal signal and precursory thermal increases are due to the slow ascent of andesitic magma, whereas the more rapid rise, effusion, and cooling of basaltic magmas at Kliuchevskoi give rise to a discontinuous thermal pattern. Documentation, analysis, and understanding of these characteristics contribute to the understanding of thermal signals and aid the development of monitoring algorithms and early warning techniques.