The gauge-data.txt template defaults to using the unit system used by your database, in most cases this is US imperial. It's easy enough to change, you could override the units in skin.conf or in weewx.conf. weewx.conf would be better as it will survive any upgrades/updates whereas skin.conf may be overwritten. In weewx.conf locate the [StdReport] [SteelSeries]] section and add a [[[Units]]] stanza as follows:
skin = ss
HTML_ROOT = /var/www/html/weewx/ss
group_altitude = meter
group_pressure = hPa
group_rain = mm
group_rainrate = mm_per_hour
group_temperature = degree_C
group_speed = km_per_hour
You can change the above settings to suit, the only caveat is you need to use weeWX unit codes. A list of available codes can be found in the Units appendix to the weeWX Customization Guide http://weewx.com/docs/customizing.htm#units
. Look in the Unit options column of the Unit groups, members and options table.
You will need to stop/sart weewx for the changes to take effect.
I am using the steel series gauges with a metric setup on my web site http://torolmen.no/vaerside-for-torolmen.
It all works fine except for a tiny detail, the hover menus are displaying numbers with 12 digits (see attached image).
I am not able to find out how this can be controlled.