A set of eight polymer clad silica (PCS) fibers from Quartz & Silice with varying water content, cladding thickness, and cladding material type have been exposed to 50 nsec wide X-ray pulses at different temperatures (-45°C, -25°C, 0°C, +25°C) in order to study the effect of fiber parameters and temperature on the extent of X-ray induced transient attenuation at typical LED wavelengths (820 nm, 900 nm, 940 nm, 1060 nm). Our results indicate that, relative to other fiber parameters, the presence of water suppresses the transient attenuation in these fibers especially at the longer wavelengths and lower temperatures. Both the peak transient attenuation, ap, and the normalized transient attenuation, α (t)/αρ, increased with decreasing temperature as one might expect for thermally-limited recovery processes. The peak trans-ient attenuation also increased with decreasing wavelength, with the wavelength dependence being stronger in the wet fibers. Within the limits of this experiment, the cladding characteristics had no effect on the fiber response to irradiation. Thus, in spite of the fact that the presence of water leads to greater intrinsic fiber attenuation between 900 nm and 1000 nm, its presence is beneficial to low temperature fiber behavior in an ionizing environment.