LEEWARD OLYMPICS
The northern and eastern slopes of the Olympic Mountains constitute the leeward side because the prevailing winter winds at this latitude in the northern hemisphere come from the southwest. Accordingly, the leeward side is sheltered from storms by the Windward Olympics, the mass of peaks to the south and west. As a consequence, the northern and eastern slopes receive much less precipitation because they occupy what is called the rain shadow of the mountains. The northeastern Olympics—or the Jupiter Hills as they were once called—have the lightest precipitation, from 20 to 30 inches yearly. As one goes west or south from the northeastern apex, the annual precipitation gradually increases (at the rate of about an inch per mile). Although these slopes lie within the bounds of the Leeward Olympics, they gradually phase, at the western and southern extremities, into the windward belt. Of course no sudden break occurs; one cannot draw a line and call one side the windward, the other the leeward. The boundary is approximate.
Because the northern and eastern sides of the Olympics are steeper than the southern and western slopes, the Leeward Olympics constitute only 40 percent of the total area included in the mountains. However, the peaks are generally higher in this section, and therefore the area contains as much, or perhaps more, of the high country as do the Windward Olympics.