As high readout channel density and compact design become the norm for HEP detectors so is the detector cooling at temperatures below the experimental site dewpoint. This increases the importance of humidity and temperature monitoring systems that are also adapted to the detector environment. The proposed systems for temperature and humidity monitoring are developed targeting compactness, cost, and seamless integration to the CMS DSS/DCS systems. Therefore, this paper presents a novel design for a standalone system, able to condition up to 24 temperature sensors. The proposed temperature monitoring system is aimed at many hundreds of RTD sensors with modest space and price requirements. For humidity monitoring, we have identified a potential sensing element and designed, built and tested the conditioning electronics capable of nullifying the capacitance of the long cables.