ESP8266 get weather from Weather Underground

esp-wunderground.ino

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#include <ESP8266WiFi.h>
#ifndef min
#define min(x,y) (((x)<(y))?(x):(y))
#endif
#ifndef max
#define max(x,y) (((x)>(y))?(x):(y))
#endif
#include <ArduinoJson.h>

const char SSID[]     = "********";
const char PASSWORD[] = "***************";

// Use your own API key by signing up for a free developer account.
// http://www.wunderground.com/weather/api/
#define WU_API_KEY "****************"

// Specify your favorite location one of these ways.
//#define WU_LOCATION "CA/HOLLYWOOD"

// US ZIP code
//#define WU_LOCATION ""
#define WU_LOCATION "90210"

// Country and city
//#define WU_LOCATION "Australia/Sydney"

// 5 minutes between update checks. The free developer account has a limit
// on the  number of calls so don't go wild.
#define DELAY_NORMAL    (5*60*1000)
// 20 minute delay between updates after an error
#define DELAY_ERROR     (20*60*1000)

#define WUNDERGROUND "api.wunderground.com"

// HTTP request
const char WUNDERGROUND_REQ[] =
    "GET /api/" WU_API_KEY "/conditions/q/" WU_LOCATION ".json HTTP/1.1\r\n"
    "User-Agent: ESP8266/0.1\r\n"
    "Accept: */*\r\n"
    "Host: " WUNDERGROUND "\r\n"
    "Connection: close\r\n"
    "\r\n";

void setup()
{
  Serial.begin(115200);

  // We start by connecting to a WiFi network
  Serial.println();
  Serial.println();
  Serial.print(F("Connecting to "));
  Serial.println(SSID);

  WiFi.begin(SSID, PASSWORD);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(F("."));
  }

  Serial.println();
  Serial.println(F("WiFi connected"));
  Serial.println(F("IP address: "));
  Serial.println(WiFi.localIP());
}

static char respBuf[4096];

void loop()
{
  // TODO check for disconnect from AP

  // Open socket to WU server port 80
  Serial.print(F("Connecting to "));
  Serial.println(WUNDERGROUND);

  // Use WiFiClient class to create TCP connections
  WiFiClient httpclient;
  const int httpPort = 80;
  if (!httpclient.connect(WUNDERGROUND, httpPort)) {
    Serial.println(F("connection failed"));
    delay(DELAY_ERROR);
    return;
  }

  // This will send the http request to the server
  Serial.print(WUNDERGROUND_REQ);
  httpclient.print(WUNDERGROUND_REQ);
  httpclient.flush();

  // Collect http response headers and content from Weather Underground
  // HTTP headers are discarded.
  // The content is formatted in JSON and is left in respBuf.
  int respLen = 0;
  bool skip_headers = true;
  while (httpclient.connected() || httpclient.available()) {
    if (skip_headers) {
      String aLine = httpclient.readStringUntil('\n');
      //Serial.println(aLine);
      // Blank line denotes end of headers
      if (aLine.length() <= 1) {
        skip_headers = false;
      }
    }
    else {
      int bytesIn;
      bytesIn = httpclient.read((uint8_t *)&respBuf[respLen], sizeof(respBuf) - respLen);
      Serial.print(F("bytesIn ")); Serial.println(bytesIn);
      if (bytesIn > 0) {
        respLen += bytesIn;
        if (respLen > sizeof(respBuf)) respLen = sizeof(respBuf);
      }
      else if (bytesIn < 0) {
        Serial.print(F("read error "));
        Serial.println(bytesIn);
      }
    }
    delay(1);
  }
  httpclient.stop();

  if (respLen >= sizeof(respBuf)) {
    Serial.print(F("respBuf overflow "));
    Serial.println(respLen);
    delay(DELAY_ERROR);
    return;
  }
  // Terminate the C string
  respBuf[respLen++] = '\0';
  Serial.print(F("respLen "));
  Serial.println(respLen);
  //Serial.println(respBuf);

  if (showWeather(respBuf)) {
    delay(DELAY_NORMAL);
  }
  else {
    delay(DELAY_ERROR);
  }
}

bool showWeather(char *json)
{
  StaticJsonBuffer<3*1024> jsonBuffer;

  // Skip characters until first '{' found
  // Ignore chunked length, if present
  char *jsonstart = strchr(json, '{');
  //Serial.print(F("jsonstart ")); Serial.println(jsonstart);
  if (jsonstart == NULL) {
    Serial.println(F("JSON data missing"));
    return false;
  }
  json = jsonstart;

  // Parse JSON
  JsonObject& root = jsonBuffer.parseObject(json);
  if (!root.success()) {
    Serial.println(F("jsonBuffer.parseObject() failed"));
    return false;
  }

  // Extract weather info from parsed JSON
  JsonObject& current = root["current_observation"];
  const float temp_f = current["temp_f"];
  Serial.print(temp_f, 1); Serial.print(F(" F, "));
  const float temp_c = current["temp_c"];
  Serial.print(temp_c, 1); Serial.print(F(" C, "));
  const char *humi = current[F("relative_humidity")];
  Serial.print(humi);   Serial.println(F(" RH"));
  const char *weather = current["weather"];
  Serial.println(weather);
  const char *pressure_mb = current["pressure_mb"];
  Serial.println(pressure_mb);
  const char *observation_time = current["observation_time_rfc822"];
  Serial.println(observation_time);

  // Extract local timezone fields
  const char *local_tz_short = current["local_tz_short"];
  Serial.println(local_tz_short);
  const char *local_tz_long = current["local_tz_long"];
  Serial.println(local_tz_long);
  const char *local_tz_offset = current["local_tz_offset"];
  Serial.println(local_tz_offset);
  return true;
}

Apparently, the Weather Underground API was shut down back in 2018:
https://apicommunity.wunderground.com/weatherapi/topics/end-of-service-for-the-weather-underground-api

so this sketch cannot work.

OpenWeatherMap offers similar functionality and free APIs (for infrequent use).
Maybe worth trying?