BME280 Accuracy for Relative Humidity

I purchased a BME280 and a cheap Humidity/Temp sensor from Amazon Link.

I noticed the BME280 tends to read rather high (59% in my office with a temp of 72F); however, the product from Amazon reads 70F @ 50% humidity.

How would I accurately calibrate the BME280? Or, rather which one IS the accurate reading?

Or, rather which one IS the accurate reading?

I would give more trust into the BME280 but into the chip not into a cheap Chinese breakout board. Do you use the chip? If yes, post your PCB layout, it’s probably not according the datasheet.
Most cheap humidity sensors (including the BME280) are not very accurate. +/- 3%RH is about mid-range but again, if you have to choose, I would select the BME280 over the ultra-cheap weather station.

I am using the BME280 breakout board from DFRobot. I am simply running wires directly from the 3V output of my board to the breakout board. I'll be running this sensor in a very high humidity environment (90-100%).

Ideally, I would to stick with a breakout board. Do you have another suggestion on a better sensor/board? I purchased a small enclosure and put some holes in it, coated the breakout board in conformal coating (with the exception of the sensor itself), and I may even put some polyester inside of the enclosure to keep particulates from getting inside of it.

I found these two from Honeywell, but they are definitely pricey.

https://sensing.honeywell.com/HIH-4031-001-humidity-sensors

The 4031 is anti-condensing, but I can’t find a breakout board. I don’t think it’s necessary though, but I would need a regulator to step up the 3.3V.

The 4031 is anti-condensing, but I can't find a breakout board. I don't think it's necessary though, but I would need a regulator to step up the 3.3V.

What do you call the Sparkfun board then? That is a breakout board.

You can use the 5V pin of the Arduino UNO to power that board.

I'll be running this sensor in a very high humidity environment (90-100%).

And what temperature range?

Most consumer humidity sensors tend to have outages if the humidity stays at 100% (condensing) for some time. Sometimes the sensor has to be dried before used again. So in your very wet environment a sensor specialized for the environment might be a good idea.

I think the Sparkfun board is the 4030 I think which is not the anti-condensing unit.

The temp needs to around 60F.

I think the Sparkfun board is the 4030 I think which is not the anti-condensing unit.

You're right. At least the board could act as a breakout for a HIH4031. Buying one board and desolder the 4030 to solder a 4031 is probably cheaper than getting your own boards.