The North China Plain has been identified as a global hotspot for ammonia (NH₃). To date, NH₃ surface observations in the region have mostly been obtained by passive samplers with a time resolution of weeks (e.g., AMoN-China), and few studies have been performed with fast-response instruments. Thus, the detailed temporal variations of NH₃ concentrations are still unclear in the region. From December 2017 to February 2018, NH₃ concentrations were observed at a high-temporal resolution of 1 Hz by using the Picarro online instrument at the Xianghe, a rural site between the megacities of Beijing and Tianjin. During the campaign, the hourly NH₃ concentrations ranged from 0.8 to 483.3 ppb, with an overall mean of 16.7 ± 19.7 ppb, which was considerably higher than those reported at other sites. In addition, the diurnal profile showed a notable increase of NH₃ concentrations in the morning, which was likely due to dew evaporation. While the monthly difference of NH₃ concentrations in winter was most likely driven by temperature, the elevated biomass burning may have also a considerable effect. The presented observations could provide insights into the dynamic characteristics of NH₃ during haze pollution and provide a unique dataset to validate atmospheric chemistry and transport models at high-temporal resolutions.