DHT21 - values spikes

Hello!

I'm having a problem maybe? or I'm not sure.

My sensor is giving me correct values, but every couple of measurements it gives me a little spike?

These are the last 30 measurements:

Time Temp Hum
2017-02-03 02:16:42 12.30 75.60
2017-02-03 02:16:11 12.40 75.60
2017-02-03 02:15:40 13.00 76.10
2017-02-03 02:15:10 12.30 76.00
2017-02-03 02:14:39 12.50 76.00
2017-02-03 02:14:08 12.50 75.80
2017-02-03 02:13:37 13.10 75.70
2017-02-03 02:13:06 15.60 76.90
2017-02-03 02:12:35 12.10 75.20
2017-02-03 02:12:05 12.30 75.30
2017-02-03 02:11:34 12.20 75.50
2017-02-03 02:11:03 12.40 75.50
2017-02-03 02:10:32 12.30 75.70
2017-02-03 02:10:01 12.40 75.30
2017-02-03 02:09:30 14.50 76.30
2017-02-03 02:09:00 13.70 75.80
2017-02-03 02:08:29 13.40 75.20
2017-02-03 02:07:58 12.50 74.80
2017-02-03 02:07:27 12.40 74.70
2017-02-03 02:06:56 14.70 75.80
2017-02-03 02:06:25 12.50 74.80
2017-02-03 02:05:55 12.70 74.90
2017-02-03 02:05:24 12.40 74.90
2017-02-03 02:04:53 15.50 76.30
2017-02-03 02:04:22 12.50 74.60
2017-02-03 02:03:51 12.70 74.70
2017-02-03 02:03:20 14.70 75.80
2017-02-03 02:02:49 14.50 75.70
2017-02-03 02:02:19 12.30 74.70
2017-02-03 02:01:48 12.40 74.90
2017-02-03 02:01:17 12.50 75.00
2017-02-03 02:00:46 13.30 75.40
2017-02-03 02:00:15 13.20 75.30
2017-02-03 01:59:44 14.40 75.70
2017-02-03 01:59:14 12.50 74.80

As you can see it goes every 30 seconds, and do you notice this spikes for +1 or +1.5 degeress up?
On some measurements it goes the sames values -1 or -1.5 degress.

I do not belive that weather changes that often

Do you use it outdoors? Did you take action against wind to the sensor (protection shield)? Did you check them in a temperature controlled area (p.e. inhouse)?

Could be in your code (resolution of ADC + resolution of your calculations for temperature).

Just for future reference, after replacing sensor everything is normal.
It was faulty sensor.

Thanks