Adventitiously I observed my desktop cannot do NTP update, suspecting it is because of proxy. I did some triage then google.

Credit/refer to How to use ntpdate behind a proxy?

By triage, switch off NTP, modify time, then turn on NTP via system date/time setting is not working

$ dmesg | tail 
[1328911.777687] systemd-timedated[8385]: Set NTP to disabled
[1328918.627650] systemd-timedated[8385]: Changed local time to Wed Jan 21 17:26:35 2015
[1328953.967353] systemd-timedated[8385]: Set NTP to enabled

Turns out there is wonderful conjuration using http header

$ sudo date -s "$(curl -sD - google.com | grep ^Date: | cut -d' ' -f3-6)Z"
Wed Jan 21 18:45:45 CST 2015