OpenWeatherMapAppsScript.js

function PRECIPITATION_YESTERDAY() {
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var rainfallSheet = ss.getSheetByName("Brooklyn daily rainfall");
  var hourlyWeatherSheet = ss.getSheetByName("Brooklyn hourly weather");
  // DEPENDENCY: Assumes worksheets exist with the above to names.
  
  var endpoint = "https://api.openweathermap.org/data/2.5/onecall/timemachine";
  
  var unixTimeYesterday = Math.floor((new Date((new Date).setDate(((new Date).getDate() - 1)))).valueOf() / 1000);
  
  // Sign up for an OpenWeatherMap account and then navigate to https://home.openweathermap.org/api_keys
  // to generate an API key. The free tier allows for 1,000 API calls per day across a selection of endpoints.   
  var queryParams = {
    "lat": "40.6560831", // coords for Prospect Park
    "lon": "-73.9653906", // replace with your coords
    "dt": unixTimeYesterday,
    "units": "imperial",
    "appid": "YOUR_OPENWEATHERMAP_APP_KEY_HERE" // replace with your OpenWeatherMap API key
  };
  
  var queryString = Object.keys(queryParams).map(
    function(key) { return key.toString() + "=" + queryParams[key] }
  ).join("&");
  
  var response = UrlFetchApp.fetch(endpoint + "?" + queryString);
  
  var data = JSON.parse(response);
  
  var mmRain = data.hourly.reduce((sum,hour) => {
    if (hour["rain"] && hour["rain"]["1h"]) {
      return sum + hour["rain"]["1h"]
    } else {
      return sum
    }
  }, 0);

  var hourlyData = data.hourly.map(hour => {
                                   var rain;
                                   if (hour["rain"] && hour["rain"]["1h"]) { rain = hour["rain"]["1h"] }
                                   return [
                                     readable_date(hour.dt),
                                     readable_date(hour.sunrise),
                                     readable_date(hour.sunset),
                                     hour.temp,
                                     hour.feels_like,
                                     hour.dew_point,
                                     hour.humidity,
                                     hour.clouds,
                                     rain,
                                     hour.pressure,
                                     hour.wind_deg,
                                     hour.wind_gust,
                                     hour.wind_speed,
                                     data.lat,
                                     data.lon
                                   ];
                                 });

  rainfallSheet.appendRow([readable_date(data.current.dt), mmRain]);
  hourlyData.forEach(row => hourlyWeatherSheet.appendRow(row))
}

function readable_date(date) {
  return new Date(date * 1000).toISOString().replace("T", " ").replace("Z", "");
}