Daily Weather Forecast using Weather API in ASP.Net

I managed to create a sample. You will need to register and get an AppId from here.

HTML

<asp:TextBox ID="txtCity" runat="server" Text="Mumbai" />
<asp:Button Text="Get Weather Information" runat="server" OnClick="GetWeatherInfo" />
<hr />
<table id = "tblWeather" runat = "server" border="0" cellpadding="0" cellspacing="0" visible = "false">
    <tr>
        <th colspan = "2">
            Weather Information
        </th>
    </tr>
    <tr>
        <td rowspan="3">
            <asp:Image ID="imgWeatherIcon" runat="server" />
        </td>
    </tr>
    <tr>
        <td>
            <asp:Label ID="lblCity_Country" runat="server" />
            <asp:Image ID="imgCountryFlag" runat="server" />
            <asp:Label ID="lblDescription" runat="server" />
        </td>
    </tr>
    <tr>
        <td>
            Temperature:
            <asp:Label ID="lblTemperature" runat="server" />
            (Min:
            <asp:Label ID="lblTempMin" runat="server" />
            Max:
            <asp:Label ID="lblTempMax" runat="server" />) Humidity:
            <asp:Label ID="lblHumidity" runat="server" />
        </td>
    </tr>
</table>

Namespaces

using System.Net;
using System.Web.Script.Serialization;

Code

protected void GetWeatherInfo(object sender, EventArgs e)
{
    string appId = "<App Id>";
    string url = string.Format("http://api.openweathermap.org/data/2.5/weather?q={0}&units=metric&APPID={1}", txtCity.Text.Trim(), appId);
    using (WebClient client = new WebClient())
    {
        string json = client.DownloadString(url);
        if (json.IndexOf("Error") == -1)
        {
            WeatherInfo weatherInfo = (new JavaScriptSerializer()).Deserialize<WeatherInfo>(json);
            lblCity_Country.Text = weatherInfo.name + "," + weatherInfo.sys.country;
            imgCountryFlag.ImageUrl = string.Format("http://openweathermap.org/images/flags/{0}.png", weatherInfo.sys.country.ToLower());
            lblDescription.Text = weatherInfo.weather[0].description;
            imgWeatherIcon.ImageUrl = string.Format("http://openweathermap.org/img/w/{0}.png", weatherInfo.weather[0].icon);
            lblTemperature.Text = string.Format("{0}°С", Math.Round(weatherInfo.main.temp, 1));
            lblTempMin.Text = string.Format("{0}°С", Math.Round(weatherInfo.main.temp_min, 1));
            lblTempMax.Text = string.Format("{0}°С", Math.Round(weatherInfo.main.temp_max, 1));
            lblHumidity.Text = weatherInfo.main.humidity.ToString();
            tblWeather.Visible = true;
        }
    }
}

public class WeatherInfo
{
    public Coord coord { get; set; }
    public Sys sys { get; set; }
    public List<Weather> weather { get; set; }
    public Main main { get; set; }
    public int dt { get; set; }
    public string name { get; set; }
}

public class Coord
{
    public double lon { get; set; }
    public double lat { get; set; }
}

public class Sys
{
    public string country { get; set; }
}

public class Weather
{
    public string main { get; set; }
    public string description { get; set; }
    public string icon { get; set; }
}

public class Main
{
    public double temp { get; set; }
    public double temp_min { get; set; }
    public double temp_max { get; set; }
    public int humidity { get; set; }
}

Screenshot