Objectives were to use within-barn measurements of temperature-humidity index (THI) to evaluate its effect on (1) Pregnancies per AI (P/AI) relative to THI at or near AI; (2) postpartum disease incidence rates (DZ30); and (3) exit from the herd (E30) relative to THI near parturition. Temperature and humidity measurements were collected hourly on 5 farms using HOBOware data loggers. Hourly measurements were averaged daily. The effect of THI on P/AI was evaluated using a THI threshold of 72 on the day of AI (THI1) or by 3-d (THI3) and 7-d (THI7) rolling averages (day of AI and prior). The DZ30 and E30 were analyzed by THI on the day of parturition (THIC), THI 7 d before and after parturition (THI14), 7 d before parturition (PreTHI), and the day of parturition plus 6 d after (PostTHI). The DZ30 and E30 were analyzed by a 68 THI threshold and represent a 30-d risk period. DZ30 represented a minimum of 1 reported event of: displaced abomasum, milk fever, metritis, retained placenta, ketosis, or mastitis. Pregnancies per AI were lower (P < 0.01) for AI occurring at ≥72 THI threshold using all 3 THI approximations. Mean P/AI were 38.7% (n = 9,334) vs 32.5% (n = 1,140) for THI1 <72 or ≥72, 34.8% (n = 9,291) vs 30.3% (n = 1,074) for THI3 <72 or ≥72, and 38.8% (n = 9,392) vs 28.9% (n = 748) for THI7 <72 or ≥72. The DZ30 for THI ≥68 vs THI <68 tended to be different for THIC (P = 0.08), was similar for PostTHI (P = 0.15) but it was greater for THI14 (P = 0.01) and PreTHI (P = 0.02). Mean (95% CI) DZ30 was 26.3% (24.3–28.4%) vs 30.3% (27.9–32.9%) for THI14 <68 (n = 2,381) or ≥68 (n = 1,922) and was 26.3% (24.3–28.5%) vs 30.2% (27.8–32.7%) for PreTHI <68 (n = 2,388) or ≥68 (n = 1,905). Relative risk (RR) of DZ30 (95% CI) was greater than 1 for THI14 ≥68:THI14 <68 (1.15, 1.03–1.29) and PreTHI ≥68:PreTHI <68 (1.15, 1.02–1.29). Thus, attributable risk (AR) of THI14 ≥68 to DZ30 is 13.2% and of PreTHI ≥68 is 12.9%. Rates of E30 were similar (P > 0.10) for all THI measurements using a 68-unit threshold. We conclude that THI before insemination reduces P/AI, that THI around parturition affects 30-d postpartum disease risk with prepartum THI having the greatest effect. Also, THI around parturition does not strongly affect postpartum 30-d exit probabilities.