I had the same problem with my weather forecast. I made a subscription for an API 3.0 key and modified the config in this way:
{
module: "MMM-OpenWeatherForecast",
position: "top_right",
header: "Wetter in Mülheim",
config: {
apiBaseURL: "https://api.openweathermap.org/data/3.0/onecall?",
apikey: "xxxxxxxxxxxxxxxxxxxxxxxx", //only string here
latitude: 51.xxxxxxxx, //number works here
longitude: 6.9xxxxxxxx, //so does a string
updateInterval: 45,
iconset: "3c",
maxDailiesToShow: 4,
maxHourliesToShow: 4,
label_hourlyTimeFormat: "k[ Uhr]",
label_sunriseTimeFormat: "k:mm", // change the format for this one
label_days: ["So", "Mo", "Di", "Mi", "Do", "Fr", "Sa"]
In addition I added "https://api.openweathermap.org/data/3.0/onecall?" as mentioned by @Ray in the node_helper.js in the weather module. The update intervall is 45 minutes - which means below 1000 calls per month
The module is running again!!!
Thx to this community and forum,
Chris