$re = '/air_temp": \K[\d.]+/';
$str = ' {
"observations": {
"notice": [
{
"copyright": "Copyright Commonwealth of Australia 2017, Bureau of Meteorology. For more information see: http://www.bom.gov.au/other/copyright.shtml http://www.bom.gov.au/other/disclaimer.shtml",
"copyright_url": "http://www.bom.gov.au/other/copyright.shtml",
"disclaimer_url": "http://www.bom.gov.au/other/disclaimer.shtml",
"feedback_url": "http://www.bom.gov.au/other/feedback"
}
],
"header": [
{
"refresh_message": "Issued at 12:11 pm EST Tuesday 11 July 2017",
"ID": "IDN60901",
"main_ID": "IDN60902",
"name": "Canberra",
"state_time_zone": "NSW",
"time_zone": "EST",
"product_name": "Capital City Observations",
"state": "Aust Capital Territory"
}
],
"data": [
{
"sort_order": 0,
"wmo": 94926,
"name": "Canberra",
"history_product": "IDN60903",
"local_date_time": "11/12:00pm",
"local_date_time_full": "20170711120000",
"aifstime_utc": "20170711020000",
"lat": -35.3,
"lon": 149.2,
"apparent_t": 5.7,
"cloud": "Mostly clear",
"cloud_base_m": 1050,
"cloud_oktas": 1,
"cloud_type_id": 8,
"cloud_type": "Cumulus",
"delta_t": 3.6,
"gust_kmh": 11,
"gust_kt": 6,
"air_temp": 9.0,
"dewpt": 0.2,
"press": 1032.7,
"press_qnh": 1031.3,
"press_msl": 1032.7,
"press_tend": "-",
"rain_trace": "0.0",
"rel_hum": 54,
"sea_state": "-",
"swell_dir_worded": "-",
"swell_height": null,
"swell_period": null,
"vis_km": "10",
"weather": "-",
"wind_dir": "WNW",
"wind_spd_kmh": 7,
"wind_spd_kt": 4
},
{
"sort_order": 1,
"wmo": 94926,
"name": "Canberra",
"history_product": "IDN60903",
"local_date_time": "11/11:30am",
"local_date_time_full": "20170711113000",
"aifstime_utc": "20170711013000",
"lat": -35.3,
"lon": 149.2,
"apparent_t": 4.6,
"cloud": "Mostly clear",
"cloud_base_m": 900,
"cloud_oktas": 1,
"cloud_type_id": 8,
"cloud_type": "Cumulus",
"delta_t": 2.9,
"gust_kmh": 9,
"gust_kt": 5,
"air_temp": 7.3,
"dewpt": 0.1,
"press": 1033.1,
"press_qnh": 1031.7,
"press_msl": 1033.1,
"press_tend": "-",
"rain_trace": "0.0",
"rel_hum": 60,
"sea_state": "-",
"swell_dir_worded": "-",
"swell_height": null,
"swell_period": null,
"vis_km": "10",
"weather": "-",
"wind_dir": "NW",
"wind_spd_kmh": 4,
"wind_spd_kt": 2
}
]
}
}';
preg_match($re, $str, $matches, PREG_OFFSET_CAPTURE, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php