<p>Leaf blight, caused by <i>Drechslera avenae</i>, is one of the most important foliar diseases of oat in North Western India. A study aimed to assess the effect of date of sowing and weather variables on leaf blight disease and green fodder quality traits. The study was conducted over two years, from the winter of 2021–22 to 2022–23, at five sowing dates with two oat genotypes, namely OL 14 and OL 15. The date of sowing significantly influenced the severity of leaf blight and green fodder yield. The lowest disease severities (28.80 and 36.46%) were noticed in the crop sown on the 7th and 23rd of October, with 198.51 and 249.79 area under disease progress curve (AUDPC) values. The highest severity was recorded on the crop planted in December with more than 60% severity and 416.21 AUDPC. The maximum green fodder yield was obtained from genotype OL 14 (687.9 and 565.8 q ha^− 1) from the crop sown on the 7th and 23rd of October, respectively. An increase in disease severity was noticed with a delay in sowing time. Various fodder quality parameters, such as dry matter content, crude protein, acid detergent fibre and neutral detergent fibre, were analysed in green fodder harvested at fifty per cent flowering from different dates of sowing. 1st and 2nd dates of sowing showed higher dry matter content (19.47&amp; 18.30%) and low crude protein (9.83 &amp; 12.00%) in the green fodder while, cell wall constituents like acid detergent fibre (38.20 &amp; 34.35%) and neutral detergent fibre (62.00 &amp; 59.23%) were found to be high in timely sown crop in comparison to late sown crop during both the cropping seasons. The effect of weather parameters like maximum and minimum temperature, morning and evening relative humidity and rainfall were recorded in staggered sowing dates and found that the maximum and minimum temperature were significantly negatively correlated with the severity of disease on the crop sown on the 1st and 2nd dates of sowing and positively significantly correlated with evening relative humidity.</p>