Heat stress in dairy cattle negatively affects welfare and production. Holding pen and feedline sprinklers are effective cooling strategies, but have the potential to spray the ground if cows are not present. A novel cooling strategy is to use individual showers in the parlor, allowing controlled water application on each cow. Our objective was to quantify the cooling effectiveness of soaking dairy cattle during milking in the parlor. Eight pens (n = 8) of lactating Holstein cows were enrolled over 4 periods. Two pens/period were tested during 1 milking/d with 3 d unsprayed (control) and 3 d sprayed (1 min, 10.9 ± 2.3 L, mean ± SD). Fifteen focal cows/pen were evaluated 30 s before and after treatment application for respiration rate (RR) and body temperature (BT), measured from continuous video recordings and vaginally indwelling data loggers (1-min intervals), respectively. Microclimate (temperature and relative humidity) of the parlor was measured at 5-min intervals and converted to temperature-humidity index (THI; range 65.3–81.3). Linear mixed models were used to evaluate treatment and THI effects and their interaction. Cows mostly maintained homeothermy: BT did not differ between treatments before or after the treatment period (38.5 ± 0.04°C, mean ± SE; regardless of treatment or time point; P = 0.65). BT had a positive linear relationship with THI (P < 0.001): for every 10-unit THI change, BT increased by 0.2°C, and starting values > 38.6°C were observed when THI > 72. Elevated RR is an early heat-stress indicator. Beforehand, RR did not differ between treatments (control vs. spray: 56.7 ± 3.7 vs. 57.7 ± 3.7 breaths/min; P = 0.64). RR had a positive linear relationship with THI (P < 0.001): for every 10-unit THI increase, RR increased by 24 breaths/min, and starting values > 60 breaths/min were observed when THI > 70. The spray effectively reduced RR (control vs. spray: 57.0 ± 3.3 vs. 47.4 ± 3.3 breaths/min; P = 0.004) and also decreased the effects of THI on RR (treatment × THI interaction; P < 0.001): for every 10-unit THI change, RR increased by 23 vs. 18 breaths/min in the control vs. spray treatments, respectively. Individual showers in the parlor were effective at reducing RR.