It is advisable not to use document.querySelector if you're using Angular or React. React/Angular will have the browser repaint the DOM by making updates in the "root" div element of the index.html file whenever there is new data available to update. Also, why do you want to send a HTML file? You could have a route in Node like below

route.get('/weather', (req, res) => {
    // do your api call with axios to get weather data
   res.json(weatherData);
});

from your front-end you could make an API call to '/weather' route and consume the JSON data

axios.get('baseUrl/weather').then(res=>{
   console.log("weather data", res);
}).catch(...);

You could also fetch weather data directly from front-end like above.