How accurate is rectal temp? A rectal temperature is0.5°F (0.3°C) to 1°F (0.6°C) higher than an oral temperature. An ear (tympanic) temperature is 0.5°F (0.3°C) to 1°F (0.6°C) higher than an oral temperature. An armpit (axillary) temperature is usually 0.5°F (0.3°C)...