Pretty straightforward:
String[] cities = new String[3];
String[] zipCodes = new String[3];
for (int i = 0; i < 3; i++) {
System.out.println ("Please enter your City No." + (i + 1) + ":");
cities[i] = keyboard.nextLine().toUpperCase();
System.out.println ("Please enter your Zipcode No." + (i + 1) + ":");
zipCodes[i] = keyboard.nextLine();
}
System.out.println("------------------------------------------------------");
System.out.println("EVAN'S WEATHER FORECAST FOR: SUNDAY, OCTOBER 07, 2013");
System.out.println("------------------------------------------------------");
System.out.println("City Zip Code Temp Relative Humidity");
for (int i = 0; i < 3; i++) {
System.out.println(cities[i] +" " + zipCodes[i] +
port.getCityWeatherByZIP(zipCodes[i]).getTemperature() +
port.getCityWeatherByZIP(zipCodes[i]).getRelativeHumidity());
}