AsNoriuanswered grow question a year ago Frost dont act well, same imagine cold temp would influence, but 15 ... a bit on verge, i had few nights, even 13, i grew in static caravan, its tin can. But my late harvests after frost or snow always had almost dead and disappeared pistils
10 degrees is big swing. In canna recomend not more than 7.
Maybe few factors and you have result.