Inclement weather such as rain, snow, and fog is a constant feature of motor vehicle travel. During poor conditions, commercial truck drivers and their dispatchers must use discretion when deciding whether travel should continue and in what manner.
Federal Motor Carrier Safety Regulations (49 C.F.R. § 392.14) specifically address driving in adverse weather conditions and require commercial drivers to exercise extreme caution. How to interpret extreme caution is subject to debate. The regulation states the driver shall reduce speed when adverse weather conditions are present and cease operations when conditions become sufficiently dangerous.
However, some courts have interpreted extreme caution as placing a heightened standard of care on the commercial driver, requiring greater vigilance and attentiveness than a passenger car driver.