January 1987 "Seasonal variation in the rate of strokes, with a peak in the winter-spring and a trough in the summer-autumn, has been reported in many areas, including the United States, England, Canada, Japan, and Australia." https://www.ahajournals.org/doi/epdf/10.1161/01.STR.18.1.38
Never heard of stroke season?
06 February 2013 "Incidence for FES [first-ever stroke] was lowest in summer with significantly higher rates in winter" https://link.springer.com/article/10.1007/s10654-013-9772-4
January 1987 "Seasonal variation in the rate of strokes, with a peak in the winter-spring and a trough in the summer-autumn, has been reported in many areas, including the United States, England, Canada, Japan, and Australia." https://www.ahajournals.org/doi/epdf/10.1161/01.STR.18.1.38