I’m in search of a highly responsive and precise temperature and humidity sensor to enhance the automation of my air conditioner. My current SONOFF SNZB-02 sensor is not delivering real-time data efficiently, I’m not happy with it.
I’m seeking recommendations for a sensor with the shortest update time and excellent accuracy.
Wire a thermocouple into a Raspberry Pi, Arduino, or some ESPHome device. That’s going to be fairly cheap and very accurate.
I’m just starting to explore options for temperature sensors everywhere, and I’m seeing 5-10 minute update times, or if it changes by x degrees. Which is great for a dashboard of room temperatures, but not so great if you need accurate, up-to-date readings.
A thermocouple into hardware is a bit of programming, but you’ll have full control of how frequently data gets sent, and how accurate the data is. TCs can be very accurate, especially if you pick the right type for your temp range.
“That would be great, but it’s not possible for me to build an ESP32. Are there any ready-made solutions available?”
For easy projects with high accuracy, that list should be helpful.
Otherwise, if you’re looking for a wireless, ready-made sensor, then I’d just shop around for your specifications. If something offers a direct-app readout, chances are it’s a bit more capable than a cheap one I’d be in the market for.
How responsive and how precise do you (really) require? 
You might be able to have a highly accurate* (and highly expensive) sensor paired via esphome api to HA with a update interval of 64ms - but what for? 
Is your air conditioner even able to react that fast? How do you switch it? Can it even be triggered as fast as a sensor would update? And doesn’t it might negatively degrade the lifetime of your AC? 
Are you sure at all this is what you seeking for? 
Sounds like zigbee so only local polling. For fast (and real time) updates you want to go with local push (like esphome) 
*sensirion got some high quality sensors
UPDATE: Looks like a typical sensor response time for humility is somewhere around 5 second even for high accurate sensors
@drtanzil maybe you want to tell us how slow your zigbee sensor is to get an idea how bad the situation is?
The SONOFF SNZB-02 is really bad. it fluctuates more than 1-2 C than real temperature, I have it side by side to real meter. The SONOFF SNZB-02 also not updates every 5 sec. there is another model (Round one) with similar name which does but i’m not sure how accurate that is, I never used that one. Humidity reading fluctuates 15-20% than real data.
I don’t need Lab standard accuracy. Need a sensor that at least useable. Looking for a sensor which gives < 0.5 C fluctuation and at least updates 15-20 sec interval.
Now we have a ball park here 
The update interval is no problem at all with esphome and the linked Sensiron sensor are available with specs you expect. For example
SHT43
Digital humidity sensor with ISO17025 certification
Typ. temperature accuracy 0.48 °C
or
SHTC3
±2% (20-80%RH) Digital humidity and temperature sensor
Typ. temperature accuracy 0.1 °C
The later is also to be found in that (formerly?) dirt cheap xiaomi hygrometers that can be
owned and extended to show custom content from HA 
Xiaomi Mijia BLE Sensors — ESPHome
PVVX MiThermometer Display — ESPHome
If I remember right the advertising interval is 2.5s and measurement interval 10s by default 
