Here parameters of API respond :
{\"cod\":\"200\",\"message\":0.0045, \"city\":{\"id\":1851632,\"name\":\"Shuzenji\", \"coord\":{\"lon\":138.933334,\"lat\":34.96
First, make sure you have decoded the json.
$decodedData = json_decode($data);
Then, try accessing the object's properties and arrays like this:
echo $decodedData->list[0]->weather[0]->description;