The hygroscopic growth of aerosol particles has great influence on regional environment, meteorology, and radiation budget. Therefore, accurate observations of aerosol hygroscopic characteristics have important implications for describing aerosol hygroscopicity, studying the effects to climatic environment and expanding applications of satellite aerosol products. This study presents a method to estimate aerosol hygroscopic growth by integrating in situ meteorological and air quality data (visibility, humidity, and PM2.5). Based on this method, temporal and spatial variations of aerosol hygroscopicity at three different sites in Zhejiang, i.e., Hemu School in Hangzhou (an urbanized site), Shiyan School in Quzhou (a clean inland site), and Ouhai in Wenzhou (a coastal site). Ouhai exhibits the highest hygroscopic growth ability, while Hemu School, which lies in the central Yangtze River delta region, shows the moderate hygroscopic growth. Compared to the other two sites, Shiyan School has less hygroscopic growth during most time of the year. Among the three sites, the largest temporal variation of hygroscopic growth is found at Shiyan School, while Hemu School and Ouhai have the moderate and the least temporal variations, respectively. This study shows that the aerosol hygroscopic growth in Zhejiang varies a lot with time and space. Based on this method, the hygroscopic growth characteristics of aerosol can be described in a large temporal and spatial range, which provides important supplements for limited in situ observations.