Add Webpart zone on Masterpage in SharePoint 2010

1. In your masterpage add the webpart zone wherever you want:
   <asp:ContentPlaceHolder id="MyWebpartZone" runat="server"></asp:ContentPlaceHolder>
   
2.  Add the following tag anywhere in your layout pages
   <asp:Content ContentPlaceHolderId="WeatherPart" runat="server">
   <div>
   <WebPartPages:WebPartZone runat="server" Title="WeatherPart" ID="WeatherPart"><ZoneTemplate></ZoneTemplate></WebPartPages:WebPartZone>
   </div>
   </asp:Content>