options = {
        xaxes: [{
            tickFormatter: xTickFormatter,
            mode: "time",
            timezone: "browser"
        }],

and xTickFormatter looks like this:

function xTickFormatter (val, axis) {
    var d = new Date(val),
        h, m;

    h = d.getHours();
    m = d.getMinutes();
    m = m < 10 ? "0" + m : m;
    return [
        d.getDate(), " ", months[d.getMonth()],
        "<br>",
        h, ":", m
    ].join("");
}

months[] is an array defined earlier:
 

months = ["Jan", "Feb" . . . "Nov", "Dec"];

SELECT UNIX_TIMESTAMP(datetime_column) as unix_timestamp FROM table ORDER BY datetime_column DESC.

$query = "SELECT * FROM (SELECT * FROM outside ORDER BY id DESC LIMIT $limit) AS foo ORDER BY id ASC";

	    $result = mysql_query($query);
	    while($row = mysql_fetch_assoc($result))
	    {
	    $dataset1[] = array(($row['unixtime'] * 1000 ),$row['temperature']);
            }