Sorry for revoking this old thread - but I do have exactly the same problem.
I'm running weewx 3.8.2 on a Raspberry connected with the Renkforce WH2300 weather station using a tweaked Sofaskin (i.e. translated to German). Everything works as expected, but the dropdown menus for "Monthly summary" or "Yearly summary" contain no lists. The HTML within Sofaskin looks slightly different from Standard skin: <li><select name="noaaselect" onchange="openNoaaFile(value)"> <option>Monatliche Übersicht</option> #for $monthYear in $SummaryByMonth <option value="$monthYear">$monthYear</option> #end for </select></li> The text from the first option "Monatliche Übersicht" is displayed twice, once on the drop down menu and as its only single entry. It appears as if the label $SummaryByMonth is empty. The sequence of entries within skin.conf is not changed as compared to Standard skin. [And the HTML fragment above is from my index.html.tmpl]. I have tried to omit the fixed option "Monatliche Übersicht" - then the drop down is completely empty. Of course, the NOAA files are created as expected within the folder /var/www/html/weewx/NOAA/ Maybe it depends on booting my Rasberry - I do this once per night. Hope you have a suggestion where to search .... Thanks, Michael