nodemcu/esp8266 reads lower than expected on A0
There's a thing that you might be missing: the input resitence of the analog ports.







simulate this circuit &ndash; Schematic created using CircuitLab

When you use such 100k resistors you may have to consider the effect that it will cause to your measurement. I didn't find the correct input value but most microcontrollers with analog inputs has a input resistence about 1M. Let's assume that.

You'll have a parallel resistor circuit of a aprox 90.9k with 100kΩ and 1MΩ in parallel, causing the lower part of your voltage divider to be less than half. So the voltage in the measure point will be 1.57V. And 1.57*1023/3.3 = 484 bits.

And your 1M thermister will make things worse.

I would advise you to use something like an op amp with buffer configuration to measure what you want. You'll rise your input resistence. Or you could use a lower thermister. Resistors with >1M insert white noise in your circuit.







simulate this circuit

If you still suspecting of something else, use 10k resistors and see it working.