Cygwin
# ==== edit tzset.sh or tzset.csh depending on the shell used by cygwin ====
$ cd /etc/profile.d
$ vi tzset.sh
# === locate and edit the following line at the bottom of the file ===
#test -z "$TZ" && export TZ=$(/usr/bin/tzset)
test -z "$TZ" && export TZ='US/Central'
# === example above shows how to set on Chicago timezone ===
# === See list of all available time zones in /usr/share/zoneinfo ===
#show configured US timezones
$ cd /usr/share/zoneinfo
$ ls US
Alaska Arizona Eastern Hawaii Michigan Pacific Samoa
Aleutian Central East-Indiana Indiana-Starke Mountain Pacific-New