PHP OOP: Use an API with cURL

<?php

class OpenWeather {

    const ICON_SIZE = '@2x'; // '', '@2x' or '@4x'
    const UNITS = 'metric';

    private $api_key;

    public function __construct(string $var)
    {
        $this->api_key = $var;
    }
    public function getToday(array $coordinates): array
    {
        $array = [];
        $data = $this->callAPI($coordinates);
        if ($data !== null) {
            $array = [
                'temp'  => $data["current"]["temp"] . '°C',
                'description'  => $data["current"]["weather"][0]["description"],
                'icon'  => 'http://openweathermap.org/img/wn/' . $data["current"]["weather"][0]["icon"] . self::ICON_SIZE . '.png',
                'time'  => $this->getTimeFormated($data["current"]["dt"], $data['timezone']),
            ];
        }
        return $array;
    }
    public function getLastHours(array $coordinates): array
    {
        $array = [];
        $data = $this->callAPI($coordinates);
        if ($data !== null) {
            foreach ($data['hourly'] as $hour) {
                $array[] = [
                    'temp' => $hour["temp"] . '°C',
                    'description' => ucfirst($hour["weather"][0]["description"]),
                    'icon' => 'http://openweathermap.org/img/wn/' . $hour["weather"][0]["icon"] . self::ICON_SIZE . '.png',
                    'time' => $this->getTimeFormated($hour["dt"], $data['timezone']),
                ];
            }
        }
        return $array;
    }
    public function getTimeFormated($timestamp, $timezone): array
    {
        $date = new DateTime("@" . $timestamp);
        $date->setTimeZone(new DateTimeZone($timezone));
        return  [
            'all' => $date->format('M d H:i'),
            'date' => $date->format('M d'),
            'hour' => $date->format('H:i'),
        ];
    }
    private function callAPI(array $coordinates): ?array
    {
        $time = time();
        $latitude = $coordinates[0];
        $longitude = $coordinates[1];
        $unit = self::UNITS;
        $curl = curl_init("https://api.openweathermap.org/data/2.5/onecall/timemachine?lat={$latitude}&lon={$longitude}&dt=$time&units={$unit}&appid={$this->api_key}");
        curl_setopt_array($curl, [
            CURLOPT_CAINFO          => dirname(__DIR__) . DIRECTORY_SEPARATOR . 'data' . DIRECTORY_SEPARATOR . 'certificates' . DIRECTORY_SEPARATOR . 'openweather.cer',
            CURLOPT_RETURNTRANSFER  => true,
            CURLOPT_TIMEOUT_MS      => 1000
        ]);
        $data = curl_exec($curl);
        if ($data === false || curl_getinfo($curl, CURLINFO_HTTP_CODE) !== 200) {
            return null;
        }
        curl_close($curl);
        return json_decode($data, true);
    } 

}

<?php 

$cities = [
    'paris'         => [48.85, 2.35],
    'kerikeri'      => [-35.22, 173.94],
    'new-york'      => [40.71, -74.00],
    'hong-kong'     => [22.39, 114.10],
];

$title = 'Weather forecast';
require_once 'includes/header.php';
require_once 'class/OpenWeather.php';
$weather = new OpenWeather('4f34eb4cec4aa5200aa8b415963e297c');
?>

<p class="lead mb-5">The list below has been made through the OpenWeather API. I links the API to this website thanks to the curl extension for PHP and following <a href="/lessons/20201127_php_Use%20an%20API%20with%20cURL/">this lesson</a>.</p>
        
<div class="row">
    <?php 
    foreach ($cities as $name => $coordinates):
        $current = $weather->getToday($coordinates); 
        if (!empty($current)): ?>
            <div class="col-md-3 mb-5">
                <div class="card">
                    <div class="card-body text-center">
                        <h4><?= implode('-', array_map('ucfirst', explode('-', $name))) ?></h4>
                        <div class="small text-muted"><?= $current['time']['all'] ?></div>
                        <img src="<?= $current['icon']; ?>"/>
                        <div><?= $current['description'] ?></div>
                        <div><b><?= $current['temp'] ?></b></div>
                    </div>
                </div>
                <div class="mt-3">
                    <ul class="list-unstyled">
                        <?php $lastHours = $weather->getLastHours($coordinates); 
                        for ($i = count($lastHours) - 1; $i >= count($lastHours) - 10; $i--): ?>
                            <?php if (!empty($lastHours[$i])): ?>
                                <li class="small text-muted"><?= $lastHours[$i]['time']['hour'] . ' - <b>' . $lastHours[$i]['temp'] . '</b>  - ' . $lastHours[$i]['description'] ?></li>
                            <?php endif; ?>
                            <?php
                        endfor; ?>
                    </ul>
                </div>
            </div>
        <?php endif; ?>
    <?php endforeach; ?> 
</div>

<?php require 'includes/footer.php'; ?>