Attracting global interest, the compost bedded pack barn (CB) is a loose housing system bedded with shavings or sawdust, without the stalls and partitions found in freestall and tie-stall housing. The objective of this study was to assess relationships among compost bedded pack (CB) moisture and temperature, ambient weather conditions, cow hygiene, mastitis indicators, and bedding bacterial counts. The CB moisture and temperature are affected by ambient conditions, which in turn alter the conditions experienced by the cow and the bacteria in the bedding. The study was conducted using data from 8 CB farms in Kentucky from May 2013 to May 2014. Biweekly, one observer hygiene scored 50 cows per farm and collected CB internal temperature at 20 cm depth (CIT), moisture, nutrient profile, and bedding samples for bacteriological culture from 9 areas in each barn. Somatic cell count and high SCC prevalence (HSP, percent of cows with SCC ≥200,000 cells/mL) were collected from DHIA. The MIXED procedure of SAS 9.3 (SAS Institute, Inc., Cary, NC) was used to assess fixed effects for all models. Stepwise backward elimination was used to remove non-significant interactions (P ≥ 0.05) with all main effects remaining in the models regardless of significance. Internal temperature increased with increasing BTHI (P < 0.01) and decreased with increasing milk yield (P < 0.01). Compost moisture content decreased with increasing BTHI (P < 0.01). Herd hygiene score decreased with increasing BTHI (P < 0.01) and increased with increasing CB moisture (P = 0.02). Herd SCC and HSP both increased with increasing BTHI (P < 0.01), but did not change with compost factors. Staphylococcus (P = 0.01), streptococcus (P = 0.01), and bacillus (P = 0.03) species growth in the bedding decreased with increasing CIT while coliform species growth (P = 0.02) increased with increasing CIT. Maintaining higher internal temperature did not reduce all bedding bacteria levels. In CB farms, BTHI affected cow hygiene and udder health indicators more than CB moisture and CIT.