Prompted by weather-related disasters that occurred to several well known and highly respected Japanese climbers during the 1980s, the Japanese Alpine Club undertook a study of the weather on Mt. McKinley from 1990 to 1991 and 1992 to 2000. Instruments were emplaced and data retrieved once each year, in June during the normal climbing season. Predictably, the severe conditions created problems with instrumentation, but one complete year, and 8 partial but still useful years, of data were obtained. Air temperature, wind speed and wind direction were recorded, sometimes at several heights above the snow surface, and from 1992 air pressure was added, on an exposed rock outcrop at 5,715m altitude above Denali Pass, a short distance off the climbing route to the South (=main) Summit.

Due to the volunteer nature of the project, data processing and analysis are still in a preliminary phase but it is clear that the data will be of value beyond the original purpose of mountaineering safety. Some interesting features which have been noticed thus far include:

1. In addition to the expected diurnal and semidiurnal periodicity of temperature, there is some indication of a detectable 6-hour periodicity.

2. The diurnal temperature variation is dominant in summer as expected, but disappears completely for several months in winter, even though McKinley is well south of the Arctic Circle and the sun comes up for several hours each day through the winter.

3. Differences in dominant wind direction, probably caused by the local topography, and in rate of heating in sunlight, are clearly observed at different heights above the snow, only a few tens of centimeters apart.

From 2002 the University of Alaska has assumed the lead role in the project, with JAC continuing to provide mountaineering support. Instrument testing is now under way with a view to providing routine observations of telemetered data which can be available in real time for both mountaineering safety and a variety of other meteorological purposes.