We have conducted laboratory experiments on frozen sulfur to further study the vacuum-weathering phenomenon discovered by Nash [1987>. In this report we discuss the effect of surface temperature on the initial transient and subsequent steady-state behavior of the vacuum-sublimation rate and the UV/VIS spectral reflectance of frozen sulfur. We show that surface temperature is a dominant parameter controlling the rate of vacuum weathering of sulfur, a finding consistent with the steep vapor pressure curve of sulfur. We set limits on the prodigious sublimation rates expected for sulfur from hot spots on Io's surface and further define the range of changes that occur in the spectral reflectance of freshly frozen sulfur. These results imply that any freshly- frozen sulfur deposits on Io at typical Io hotspot temperature should display major transient changes in color (and microtexture) in a matter of hours to days. These rapid changes in spectral reflectivity should be readily detectable by high time-resolution synoptic observations of Io's spectrum in the UV/VIS by spacecraft optical instruments such as on Galileo and, in certain instances (e.g., during or immediately after large-scale Io volcanic activity), by Earthbased telescopes. Such observations should be useful in determining the frequency of occurrence, surface location, and areal scale of any sulfur volcanic activity on Io. ¿ American Geophysical Union 1988