Правильный код:
import eel
import pyowm
owm = pyowm.OWM("*****ваш код*****")
@eel.expose
def get_weather(place):
    mgr = owm.weather_manager()
    observation = mgr.weather_at_place(place)
    w = observation.weather
    temp = w.temperature('celsius')['temp']
    return "It is now " + str(temp) + "°" + " in " + place
eel.init("web")
eel.start("main.html", size=(700, 700))
<!DOCTYPE html>
<html>
<head>
	<meta charset="UTF-8">
	<title>Weatherice</title>
	<script src="eel.js"></script>
	<link rel="icon" type="image/png" href="/images/favicon.png">
	<link rel="stylesheet" href="main.css">
	<link href="https://fonts.googleapis.com/css2?family=Roboto:wght@300;400;500&display=swap" rel="stylesheet">
</head>
<body>
	<input id="location" type="text", placeholder="Enter the name of the country and city..." required="" value="New York, USA">
	<button id="show">Find out the weather</button>
    <hr noshade color="white" size="2">
	<div id="info"></div>
	<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.6.0/jquery.min.js"></script>
	<script type="text/javascript">
		// JS code for Python functions
		async function display_weather() {
			let place = document.getElementById('location').value;
			let res = await eel.get_weather(place)();
			document.getElementById('info').innerHTML = res;
		}
		jQuery('#show').on('click', function() {
			display_weather();
		});
	</script>
</body>
</html>
* {
	font-family: "Roboto", sans-serif;
	box-sizing: border-box;
	font-weight: 300;
}
body {
	background: #01b7a2; /* fallback for old browsers*/
	background: -webkit-linear-gradient(to right, #02a1b0, #00cd96); /* Chrome 10-25, Safari */
	background: linear-gradient(to right, #02a1b0, #00cd96); /* W3C, IE 10+/ Edge, Firefox */
	color: white;
	padding: 50px;
}
#location {
	display: block;
	border: none;
	background: rgba(255, 255, 255, 0.5);
	border-radius: 10px;
	padding: 20px;
	color: white;
	outline: none;
	width: 100%;
	font-size: 30px;
}
#location:placeholder {
	color: rgba(255, 255, 255, 0.5);
}
#show {
	display: block;
	border: none;
	margin-top: 15px;
	background: #ffb9af; /* fallback for old browsers*/
	background: -webkit-linear-gradient(to right, #ffc3a0, #ffafbd); /* Chrome 10-25, Safari */
	background: linear-gradient(to right, #ffc3a0, #ffafbd); /* W3C, IE 10+/ Edge, Firefox */
	border-radius: 10px;
	padding: 20px;
	color: white;
	outline: none;
	width: 100%;
	font-size: 20px;
	text-transform: uppercase;
	font-weight: bold;
	cursor: pointer;
}
#show:hover {
	opacity: .9;
}
hr {
    margin-top: 15px;
    margin-bottom: 15px;
    opacity: .5;
}
 
 
