This report was originally submitted by UbuntuFlo in https://bugs.launchpad.net/ubuntu/+source/gnome-applets/+bug/628978

This is the original report:

As you can see in the two screenshots, the timesetting of the sunrise/sunset shown in the gnome-weather-applet is linked to the local timesetting of the installed os (Ubuntu 10.04.1, 2.6.32-24-generic).
Sunrise/sunset in Buenos Aires (Argentina) should be at 07:09 am / 06:33 pm which is shown correctly in the gnome-clock-applet.
If one uses the gnome-weather-applet (Gnome-Panel) it shows the sunrise/-set at 12:09 pm / 11.33 pm.
The five hour time-difference is the time-difference between Argentina and Germany (→ timezone of installed Ubuntu).
To correct the display of weather-applet's sunrise/-set it should not use the time of the installed os but sum up/subtract the time-difference shown in gnome-clock-applet (-5 hours in this example).

--

Currently, the clock applet uses the timezone offset from the GWeatherLocation to change the timezone before formatting the sunset and sunrise strings. It looked like it would have been easy to do the same with the weather applet, but the timezone is generally not available in the WeatherLocation structure because it is not saved in gconf (and would not be in an appropriate format anyway).

To me it looks like a legitimate bug -- at least there is an inconsistency between the two applets, -- but I can't see an easy way to fix this other than make the weather applet start using GWeatherLocation.