Because of the COVID-19 outbreak, I have been monitoring my temperature to help identify if I contract the disease. Today due to a schedule change, I took my temperature orally (under the tongue) shortly after taking a normally-hot shower, and the reading was above my baseline by about 1.5°F (0.8°C). As I have not been feeling any different otherwise, I took another reading after a couple of hours, and it was normal for me.
I suspect that the first reading was high because I had been in a hot environment for several minutes shortly before taking it, but I have not been able to find clear information on the extent to which a hot shower would affect core body temperature. The closest I found was "Effects of bath water..." by Kawahara et al. that indicates elevated skin temperature for a bath, but it seems to be focused more on comfort than physiological effects.
After taking a hot shower of typical length (say, 7–8 minutes), what is the typical amount by which a human's body temperature would rise over baseline?