# BME280 initial readings

**URL:** <https://forums.pimoroni.com/t/bme280-initial-readings/20796>\
**Category:** Support\
**Created:** [November 24, 2022, 8:46pm UTC](https://forums.pimoroni.com/t/bme280-initial-readings/20796 "2022-11-24T20:46:20Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![stg](https://avatars.discourse-cdn.com/v4/letter/s/a4c791/32.png) [@stg](https://forums.pimoroni.com/u/stg)\
**Post date:** [November 24, 2022, 8:46pm UTC](https://forums.pimoroni.com/t/bme280-initial-readings/20796/1 "2022-11-24T20:46:21Z")

</div>

I have 2 x Pimoroni BME280 and they both produce the same initial reading of 21.95\*C 698.09hPa 76.34% humidity.

Using this simple code

```auto
import time
from smbus2 import SMBus
from bme280 import BME280
bus = SMBus(1)
bme280 = BME280(i2c_dev=bus)
while True:
    temperature = bme280.get_temperature()
    pressure = bme280.get_pressure()
    humidity = bme280.get_humidity()
    print('{:05.2f}*C {:05.2f}hPa {:05.2f}%'.format(temperature, pressure, humidity))
    time.sleep(1)

```

and I always get as the first line of output as…

```
21.95*C 698.09hPa 76.34%

```

followed by the correct data for example…

```
18.70*C 993.54hPa 55.88%

18.70*C 993.53hPa 56.12%

18.71*C 993.54hPa 56.06%

18.71*C 993.54hPa 55.95%

```

Does anybody know why this is?

---

<div class="post-metadata">

**Author:** ![bablokb](https://avatars.discourse-cdn.com/v4/letter/b/ee59a6/32.png) [@bablokb](https://forums.pimoroni.com/u/bablokb)\
**Post date:** [November 25, 2022, 2:41pm UTC](https://forums.pimoroni.com/t/bme280-initial-readings/20796/2 "2022-11-25T14:41:49Z")

</div>

The first read triggers the first conversion (in bme280 speak). Probably the code reads the registers faster than the conversion takes. Subsequent readings should be fine. You will find a similar behavior with other sensors as well. So it is not a bad idea just to ignore the very first measurement.