[en] Sulfur chemistry has been implemented into the regional weather forecast model HIRLAM in order to simulate sulfur fields during specific weather situations. The model calculates concentrations of sulfur dioxide in air (SO₂(a)), sulfate in air (SO₄(a)), sulfate in cloud water (SO₄(aq)) and hydrogen peroxide (H₂O₂). Modeled concentrations of SO₂(a), SO₄(a) and SO₄(aq) in rain water are compared with observations for two weather situations, one winter case with an extensive stratiform cloud cover and one summer case with mostly convective clouds. A comparison of the weather forecast parameters precipitation, relative humidity, geopotential and temperature with observations is also performed. The results show that the model generally overpredicts the SO₂(a) concentration and underpredicts the SO₄(a) concentration. The agreement between modeled and observed SO₄(aq) in rain water is poor. Calculated turnover times are approximately 1 day for SO₂(a) and 2-2.5 days for SO₄(a). For SO₂(a) this is in accordance with earlier simulated global turnover times, but for SO₄(a) it is substantially lower. Several sensitivity simulations show that the fractional mean bias and root mean square error decreases, mainly for SO₄(a) and SO₄(aq), if an additional oxidant for converting SO₂(a) to SO₄(a) is included in the model. All weather forecast parameters, except precipitation, agree better with observations than the sulfur variables do. Wet scavenging is responsible for about half of the deposited sulfur and in addition, a major part of the sulfate production occurs through in-cloud oxidation. Hence, the distribution of clouds and precipitation must be better simulated by the weather forecast model in order to improve the agreement between observed and simulated sulfur concentrations