Real world weather into Minecraft http://www.alejandromp.com/blog/2015/1/17/real-world-weather-into-minecraft

main

local wait = 60

os.loadAPI("weather")
local city = "London,uk"

while true do
  local commandBlock = peripheral.wrap("back")

  local w = weather.getWeather(city)

  local command = "weather " .. w .. " " .. wait
  print(command)
  commandBlock.setCommand(command)
  commandBlock.runCommand()

  sleep(wait)
end

weather

os.loadAPI("json")

local sun = "clear"
local rain = "rain"
local thunder = "thunder"


-- Relates id with weather
-- http://openweathermap.org/weather-conditions
local typeeq = {
  {id = 960, w = "thunder"},
  {id = 961, w = "thunder"},
  {id = 962, w = "thunder"},
}
local typeless = {
  {id = 300, w = "thunder"},
  {id = 400, w = "rain"},
  {id = 600, w = "rain"},
  {id = 700, w = "rain"},
  {id = 800, w = "clear"},
  {id = 900, w = "clear"},
  {id = 1000, w = "thunder"},
}

function getWeather(city)
  local url = "http://api.openweathermap.org/data/2.5/weather?q=" .. city
  local response = http.get(url)
  local responseStr = response.readAll()
  local obj = json.decode(responseStr)
  local id = tonumber(obj["weather"][1]["id"])
  local w = clear
  -- print("Id: " .. id)
  -- Search for an special id
  for i=1,#typeeq do
    if typeeq[i]["id"] == id then
      w = typeeq[i]["w"]
      break
    end
  end
  -- Search for an id in ranges
  for i=1,#typeless do
    if id < typeless[i]["id"] then
      w = typeless[i]["w"]
      break
    end
  end
  return w
end