System.Exception - Maybe something to do with my timer

So I have come to a problem that I have never had before and I cant find any information about my specific problem. Basically when i start the program i have a panel that displays time and weather information. When i start it, the weather is refreshed as well as the time with no problem (The problem starts at //ERROR HERE!!!) I think this probably has something to do with the timer because it works all fine without the timer but I need it so i can constantly refresh the time & weather. I will include the error at the end.

What could be the cause of this? If you need any more information let me know!

public async void WeatherInfoRefresh()
{
    TimeRefresh();

    RootObject myWeather = await CurrentWeather.GetWeather("Adelaide");

    ResultTextBlock.Text = myWeather.name + " • " + myWeather.main.temp + "°C";

    if (myWeather.weather[0].description == "broken clouds")
    {
    WeatherImage.Source = new BitmapImage(new Uri("ms-appx:///Assets/Files/AAA/brokenclouds.png"));
    }
}

My timer voids:

public void startTimer()
{
    ticker = new Timer(TimerMethod, null, 30000, 3000);
}

public void TimerMethod(object state)
{
    WeatherInfoRefresh();
}

My time refresh void:

public void TimeRefresh()
{
    //Timedate
    DayTextBlock.Text = DateTime.Now.ToString("dddd"); //ERROR HERE - This almost always works without the timer!!!
    DateTextBlock.Text = DateTime.Now.ToString("dd MMMM");
    TimeTextBlock.Text = DateTime.Now.ToString("h:mm tt");
}

And the error:

An exception of type 'System.Exception' occurred in Mashy Home Automation.exe but was not handled in user code

Additional information: The application called an interface that was marshalled for a different thread. (Exception from HRESULT: 0x8001010E (RPC_E_WRONG_THREAD))

The timer and UI run on different threads, you cannot update the UI from the timer thread.