The TMP36 is a low cost temperature sensor

float voltage = analogRead(temperaturePin) * 5.0 / 1023.0;
float temperatureC = voltage * 100 - 50;
float temperatureF = voltage * 180 - 58;
analogRead(temperaturePin) temperature [°C] temperature [°F]
140 18.43 65.17
141 18.91 66.05
142 19.40 66.93
143 19.89 67.81
144 20.38 68.69
145 20.87 69.57

At 5.0V and a 10 bit ADC the resolution is 0.49°C (0.88°F)

float voltage = analogRead(temperaturePin) * 3.3 / 1023.0;
float temperatureC = voltage * 100 - 50;
float temperatureF = voltage * 180 - 58;
analogRead(temperaturePin) temperature [°C] temperature [°F]
210 17.74 63.94
211 18.06 64.52
212 18.39 65.10
213 18.71 65.68
214 19.03 66.26
215 19.35 66.84

At 3.3V and a 10 bit ADC the resolution is 0.32°C (0.58°F)