There are two ways to create month dropdown in php. First, we can create static array of months and then loop these arrays and create a dropdwon.
But in this post we will learn month dropdown using PHP inbuilt date function.
 
 <select name="month" id="month">
           <option value="">Select Month</option>
            <?php
                      for ($i = 1; $i <= 12; $i++) {
                            $time =   mktime(0, 0, 0, $i); 
                             $label =  date('F', $time);  
                             $value =  date('n', $time);
                          echo "<option value='$value'>$label</option>";
                 }
        ?>
   </select>
DEMO
	