Surface {when} in local time for weather widget

Here's how I use this:

      local weather_widget = function(
        code,
        url,
        name
      )
        local actual_widget = wibox.widget.textbox()
        local actual_tooltip = awful.tooltip({ objects = { actual_widget } });

        actual_widget:buttons(awful.util.table.join(
          awful.button({}, 1, function () awful.spawn("firefox '" .. url .. os.time() .. "'") end)
        ))

        vicious.register(actual_widget, vicious.widgets.weather,
          function (widget, args)
            actual_tooltip:set_text(
              "City: " .. args["{city}"] ..
                "\nWind: " .. args["{windmph}"] .. "mph " ..
                "\nSky: " .. args["{sky}"] ..
                "\nHumidity: " .. args["{humid}"] ..
                "\nMeasured at: " .. os.date("%F %T", args["{when}"]))
            return name .. " " .. args["{tempf}"] .. "°F"
        end, 60 * 10, code)

        return actual_widget
      end

README.md

@@ -505,7 +505,7 @@ Supported platforms: any having Awesome and `curl` installed.
 * Argument: the ICAO station code, e.g. `"LDRI"`
 * Returns a table with string keys: `${city}`, `${wind}`, `${windmph}`,
   `${windkmh}`, `${sky}`, `${weather}`, `${tempf}`, `${tempc}`, `${humid}`,
-  `${dewf}`, `${dewc}` and `${press}`
+  `${dewf}`, `${dewc}` and `${press}`, `${when}`
 
 ### vicious.widgets.wifi
 

widgets/weather_all.lua

@@ -6,6 +6,7 @@
 -- {{{ Grab environment
 local tonumber = tonumber
 local math = { ceil = math.ceil }
+local os = { date = os.date, difftime = os.difftime, time = os.time }
 local string = { match = string.match }
 
 local spawn = require"vicious.spawn"
@@ -17,12 +18,22 @@ local helpers = require"vicious.helpers"
 -- vicious.widgets.weather
 local weather_all = {}
 
+-- copied from http://lua-users.org/wiki/TimeZone
+local function get_timezone_offset()
+    local ts = os.time()
+    local utcdate   = os.date("!*t", ts)
+    local localdate = os.date("*t", ts)
+    localdate.isdst = false -- this is the trick
+    return os.difftime(os.time(localdate), os.time(utcdate))
+end
+
 
 -- {{{ Weather widget type
 local function parse(stdout, stderr, exitreason, exitcode)
     -- Initialize function tables
     local _weather = {
         ["{city}"]    = "N/A",
+        ["{when}"]    = "N/A",
         ["{wind}"]    = "N/A",
         ["{windmph}"] = "N/A",
         ["{windkmh}"] = "N/A",
@@ -58,6 +69,19 @@ local function parse(stdout, stderr, exitreason, exitcode)
     _weather["{press}"]   = -- Pressure in hPa
        string.match(stdout, "Pressure[%s].+%((.+)[%s]hPa%)") or _weather["{press}"]
 
+    local year, month, day, hour, min =
+        string.match(stdout, "(%d%d%d%d).(%d%d).(%d%d) (%d%d)(%d%d) UTC")
+    if year ~= nil then
+       local utctable = {
+           year = year,
+           month = month,
+           day = day,
+           hour = hour,
+           min = min,
+       }
+       _weather["{when}"] = os.time(utctable) + get_timezone_offset()
+    end
+
     -- Wind speed in km/h if MPH was available
     if _weather["{windmph}"] ~= "N/A" then
        _weather["{windmph}"] = tonumber(_weather["{windmph}"])