I'm gonna say the $isdst understanding is backwards? Last week it was zero–

perl -MData::Dumper -le "print [ localtime(time - 60 * 60 * 24 * 7) ]-
+>[-1]"
0
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Update: Google on search: Daylight Saving Time (United States) 2016 began at 2:00 AM on Sunday, March 13 and ends at 2:00 AM on Sunday, November 6