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Ōno is situated within the heart of Gifu Prefecture, nestled in a landscape defined by the rugged topography of the Japanese Alps' foothills. The city's urban character is a harmonious blend of small-town residential clusters and sprawling agricultural zones, characterized by its position along the Motosu River. This river valley geography is the primary determinant of the local atmospheric behavior, as the surrounding mountains create a natural basin and surrounding hills that limits horizontal air dispersion. Elevation varies significantly across the municipality, with the valley floor serving as the primary hub of human activity. The urban–rural gradient is sharp, transitioning quickly from concentrated residential areas to dense forests and rice paddies. This surrounding greenery acts as a vital carbon sink, mitigating some of the anthropogenic emissions from local traffic and small-scale industry. However, the same terrain that provides scenic beauty also creates a vulnerability to stagnant air masses. Because Ōno is tucked away from the moderating influence of the coast, it experiences a more continental climate than cities like Nagoya. The lack of strong, consistent coastal breezes means that pollutants, whether from domestic heating or agricultural burning, can linger within the valley. Consequently, the geographic confinement of Ōno dictates a unique air quality profile where the interaction between the river's moisture and the mountain-induced wind patterns and specific microclimates governs the daily movement of particulate matter and gaseous pollutants across the region.

Air quality in Ōno follows a distinct seasonal rhythm dictated by Gifu's temperate climate and valley topography. In winter, the city often experiences temperature inversions, where cold air settles on the valley floor, trapping domestic heating emissions and particulate matter near the ground. This makes winter the most challenging period for air quality, particularly during stagnant high-pressure systems. As spring arrives, Ōno is susceptible to Kosa, the yellow dust storms originating from the Gobi Desert, which spike particulate levels despite local cleanliness. These transboundary pollutants often merge with local pollen, creating a complex respiratory challenge for sensitive groups during March and April. Summer brings high humidity and intense solar radiation, which can catalyze the formation of ground-level ozone, though the surrounding forests help scrub the air. The rainy season, or Tsuyu, typically provides the cleanest air of the year, as frequent precipitation washes aerosols from the atmosphere. Autumn is generally the optimal period for outdoor activity, characterized by exceptionally clear skies and stable air masses before the winter inversions return. For those with asthma or chronic obstructive pulmonary disease, the late winter and early spring months require caution, with a recommendation to monitor local alerts and limit prolonged exertion during stagnant mornings. By understanding these meteorological shifts, residents can better navigate the seasonal fluctuations that define the atmospheric health of this mountain-ringed community, ensuring that outdoor leisure aligns with periods of peak atmospheric clarity.