So slightly tongue in cheek but a volcanic winter from a Yosemite or Japanese super volcano would last year's. After st helens global temps were impacted due to particulate ash. Guessing if a big one goes could last year's and would be great for skiing......
http://www.telegraph.co.uk/news/2018/02/12/six-mile-lava-dome-could-trigger-volcanic-winter-kill-millions/
Of course I forgot the link
http://www.telegraph.co.uk/news/2018/02/12/six-mile-lava-dome-could-trigger-volcanic-winter-kill-millions/
Of course I forgot the link