Crash Json parse

jsonParse.ino

#include <ArduinoJson.h>

char json_string[512];
StaticJsonBuffer<512> jsonBuffer;


// "main":"Clear","description":"sky is clear"
// y tal vez temp":20,"pressure":1019,"humidity":19


char* now;
char* description;
double temp;
double pressure;
double humidity;


void setup()
{
  Serial.begin(115200);
  Serial.println(F("Press any key to post to IFTTT!"));
  getData();
}

void loop()
{
  if (Serial.available())
  {
    while (Serial.available())
      Serial.read();
  }
}

void getData()
{
    strcpy(json_string, "{\"coord\":{\"lon\":-102.3,\"lat\":21.88},\"weather\":[{\"id\":800,\"main\":\"Clear\",\"description\":\"sky is clear\",\"icon\":\"02n\"}],\"base\":\"cmc stations\",\"main\":{\"temp\":5,\"pressure\":1025,\"humidity\":56,\"temp_min\":5,\"temp_max\":5},\"wind\":{\"speed\":7.7,\"deg\":20},\"clouds\":{\"all\":5},\"dt\":1453956180,\"sys\":{\"type\":1,\"id\":3966,\"message\":0.0026,\"country\":\"MX\",\"sunrise\":1453987717,\"sunset\":1454027754},\"id\":4019233,\"name\":\"Aguascalientes\",\"cod\":200}");
    Serial.println(F("Run..."));
    JsonObject& root = jsonBuffer.parseObject(json_string);

    if (!root.success()) {
      Serial.println("parseObject() failed");
      return;
    }
    strcpy(now, root["coord"]["lon"]);
    Serial.println(now);
}