TMP36 unusual readings

Other Hardware Sensors
3

Usually a wiring problem.
The TMP36 works better if ground is directly connected to a ground pin of the Arduino.
Not via a breadboard with other devices/LEDs that use the same ground.
3.3volt supply might also be cleaner than a 5volt supply.

Use this sketch for testing.
Leo..

// TMP36 temp

void setup() {
  analogReference(INTERNAL); // use 1.1volt bandgap Aref
  Serial.begin(9600);
}

void loop() {
  Serial.println((analogRead(A0) * 0.1039) - 50.0, 1);
  delay(1000);
}

Edit:
Your code prints everything on one line.
Use Serial.println, so the next item will be printed on the next line.