WeatherStation : Mysql query join & average on tables - mysql

Question

I have two tables like that :
temperature :
+---------+---------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+---------+---------------------+------+-----+---------+----------------+
| id | bigint(20) unsigned | NO | PRI | NULL | auto_increment |
| date | datetime | YES | UNI | NULL | |
| capteur | int(11) | YES | | NULL | |
| valeur | float(3,1) | YES | | NULL | |
+---------+---------------------+------+-----+---------+----------------+
humidite :
+---------+---------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+---------+---------------------+------+-----+---------+----------------+
| id | bigint(20) unsigned | NO | PRI | NULL | auto_increment |
| date | datetime | YES | UNI | NULL | |
| capteur | int(11) | YES | | NULL | |
| valeur | int(11) | YES | | NULL | |
+---------+---------------------+------+-----+---------+----------------+
I have values recorded on those two tables, not at the same time (Around 1 record each minute).
If I enter this command, I get average values for each hour for the last 24h (so, 24 rows) :
$sql->query('SELECT hour(date) AS humhour,ROUND(AVG(valeur),1) AS avghum FROM humidite WHERE date >= (now() - INTERVAL 1 DAY) GROUP BY HOUR(date) ORDER BY DATE;');
Now, I try to get the same thing, but with both tables. Ie, for all value between 0h00 and 0h59, I want average of all temperature and average of all humidity values.
I try this command :
$result = $sql->query('
SELECT hour(temperature.date) AS hourtemp,
hour(humidite.date) AS hourhum,
ROUND(AVG(temperature.valeur),1) AS avgtemp,
ROUND(AVG(humidite.valeur),1) AS avghum
FROM temperature
INNER JOIN humidite on hour(temperature.date) = hour(humidite.date)
WHERE temperature.date >= (now() - INTERVAL 1 DAY)
GROUP BY HOUR(date)
ORDER BY DATE;');
An idea ?
Thank you !