Subsurface temperatures were measured in instrumented boreholes for about one and one-half years at depths down to 10 feet below land surface at four locations in the State. In New Castle County, temperatures were measured periodically in the field about twice a month at three sites, and, in Sussex County, they were automatically recorded every 15 minutes at one site. The depths of interest are generally in the unsaturated zone and are subject to both daily temperature fluctuations and longer seasonal changes.