Exploring Summer Heat and Moisture Trends in Inland Washington and Northern Idaho,1993-2022

Abstract

This study explores the available data sets for city weather stations across inland Washington and Northern Idaho with the following questions in mind: 1) to what degree are Inland Northwest summers heating up? 2) are Inland Northwest summers drying out? 3) do temperature and moisture trends exhibit any spatial patterns? Statistical correlative tests were conducted for temperature variables (monthly average maximum, minimum, and average temperature; cooling degree days; number of days at or exceeding 90ºF; number of days at or exceeding 95ºF; and number of warm nights, 65ºF or warmer) and moisture variables (average monthly precipitation; dew point; and relative humidity). We found general warming trends, some drying, and were unable to determine any spatial patterns given the available data. An important emergence from this investigation indicates a general deficiency in continuous temperature and moisture measuring and recording, especially at the urban landscape scale.