dht22.py

#!/usr/bin/env python

import sys
from datetime import datetime
import Adafruit_DHT as DHT

SENSOR_TYPE = DHT.DHT22
DHT_GPIO = 18

print(datetime.now().strftime('%Y/%m/%d %H:%M:%S') + "\t"),

DHT.read_retry(SENSOR_TYPE, DHT_GPIO)
for i in range(3):
    humidity, temperature = DHT.read_retry(SENSOR_TYPE, DHT_GPIO)
    if humidity is not None and temperature is not None and humidity >= 0 and humidity <= 100:
        print("{0:0.1f}\t{1:0.1f}".format(temperature, humidity))
        sys.exit(0)

print('Failed to get reading. Try again!')
sys.exit(1)