## Climatology and Trends of U.S. Surface Humidity and Temperature DIAN J. GAFFEN AND REBECCA J. ROSS Air Resources Laboratory, NOAA/Environmental Research Laboratories, Silver Spring, Maryland (Manuscript received 22 December 1997, in final form 13 April 1998) ABSTRACT Climatological annual and seasonal dewpoint, specific humidity, and relative humidity maps for the United States are presented using hourly data from 188 first-order weather stations for the period 1961–90. Separate climatologies were calculated for daytime (three observations per day between 0800 and 1600 LST), nighttime (three observations per day between 2000 and 0400 LST), and the full day (eight observations per day, every 3 h). With extended datasets for the period 1961–95, trends in these same variables and temperature are calculated for each of 170 stations and for eight regions of the country. The data show increases in specific humidity of several percent per decade, and increases in dewpoint of several tenths of a degree per decade, over most of the country in winter, spring, and summer. Nighttime humidity trends are larger than daytime trends. The specific humidity increases are consistent with upward

<h4>Background</h4>The Maltese islands are subject to substantial climate variability, with implications for ecosystems and human activities. This study leverages a 26-year dataset from the Giordan Lighthouse Background Monitoring Station (GL) on the island of Gozo to analyse short-term climate variability and its alignment with broader regional tendencies.<h4>Methods</h4>Hourly meteorological data collected from 1997 to 2022, including wind speed, wind direction, air temperature, relative humidity, and air pressure, were analysed. The study examined diurnal and annual cycles, probability distribution functions, and climate indices to characterise local climate dynamics. Qualitative comparisons were made to existing findings based in Malta to corroborate the results.<h4>Results</h4>The analysis revealed pronounced seasonal variability in all parameters. Rising air temperatures were detected, consistent with regional warming tendencies. Humidity and wind conditions showed seasonal shifts aligning with observations from other regional monitoring stations. The high-resolution dataset also captured fine-scale temporal patterns, reinforcing the critical value of localised, long-term meteorological monitoring for understanding climatic shifts.<h4>Conclusions</h4>This study underscores the value of long-term meteorological datasets in detecting climate variability, including a clear warming pattern and seasonal shifts in temperature, humidity, and wind conditions. Continuous monitoring and improved data reliability are essential for enhancing climate assessments and supporting effective adaptation strategies in the Maltese Islands.