diff --git a/WeatherStation.ino b/WeatherStation.ino
index 3a4a423..7076334 100644
--- a/WeatherStation.ino
+++ b/WeatherStation.ino
@@ -44,6 +44,10 @@ float temperature = 0.0;
 float humidity = 0.0;
 #endif // DHT_TYPE
 
+#ifdef RAIN_PIN
+bool raining = false;
+#endif // RAIN_PIN
+
 static const char TEXT_PLAIN[] PROGMEM = "text/plain";
 
 void
@@ -56,13 +60,17 @@ void
 send_metrics()
 {
     static const size_t dht_size = 228;
-    char message[dht_size + 1];
+    static const size_t rain_size = 86;
 
     size_t message_size =
 #ifdef DHT_TYPE
         dht_size +
 #endif // DHT_TYPE
+#ifdef RAIN_PIN
+        rain_size +
+#endif // RAIN_PIN
         1;
+    char message[message_size];
 
     snprintf(message, message_size,
 #ifdef DHT_TYPE
@@ -71,9 +79,19 @@ send_metrics()
              "temperature_celsius %.2f\n"
              "# HELP relative_humidity Relative humidity, in percents\n"
              "# TYPE relative_humidity gauge\n"
-             "relative_humidity %.2f\n",
-             temperature, humidity
+             "relative_humidity %.2f\n"
 #endif // DHT_TYPE
+#ifdef RAIN_PIN
+             "# HELP raining Boolean value checking if it is raining\n"
+             "# TYPE raining gauge\n"
+             "raining %d\n"
+#endif // RAIN_PIN
+#ifdef DHT_TYPE
+             , temperature, humidity
+#endif // DHT_TYPE
+#ifdef RAIN_PIN
+             , raining ? 1 : 0
+#endif // RAIN_PIN
         );
 
     server.send(200, "text/plain; version=0.0.4; charset=utf-8", message);
@@ -119,6 +137,10 @@ setup()
     dht.begin();
 #endif // DHT_TYPE
 
+#ifdef RAIN_PIN
+    pinMode(RAIN_PIN, INPUT);
+#endif // RAIN_PIN
+
     Serial.println("All set, starting the loop.");
 }
 
@@ -133,6 +155,10 @@ read_sensors()
     humidity = dht.readHumidity();
 #endif
 
+#ifdef RAIN_PIN
+    raining = (digitalRead(RAIN_PIN) == HIGH);
+#endif
+
     // Turn off the LED to indicate work is finished
     digitalWrite(LED_BUILTIN, HIGH);
 }
diff --git a/config.h.sample b/config.h.sample
index 565cadf..eff9a72 100644
--- a/config.h.sample
+++ b/config.h.sample
@@ -47,3 +47,9 @@
 //#define DHT_TYPE DHT11
 //#define DHT_TYPE DHT22
 //#define DHT_PIN D5
+
+// If you have a rain sensor (FC-37 or YL-83), connect its digital pin (not the
+// analogue one!), remove the #undef line, and uncomment and change the
+// #define RAIN_PIN line
+#undef RAIN_PIN
+//#define RAIN_PIN D0