Introduction: Arduino Weather Monitor

About: Part time tinker, Brute Force programmer. My codes are often big but are functional.

This weather monitor will consist of 2 dht11 sensors, which will sense indoor and ourdoor temperature and humidity and an ml8511 uv sensor, with onboard voltage regulator.

Step 1: Materials Required

  • arduino (I used arduino nano)
  • 8x2 digit lcd display (other displays could also be used,but it'll require mods to the code I bought it here but i made some modifications to the backlight.
  • ml8511

  • 2x potentiometer (for manual calibration ,optional)

  • dht22 or dht11 x2 (just before pblishing this instructable,I found out that dht22 is more accurate,so my decision to use dht11 was bad.I'll replace em, next month)

Step 2: The Wiring

it's as shown in the schematic

choose if you want auto calibration or manual calibration

automatic callibration could be inaccurate for having uv sensor far away from the arduino.

manual calibration is as accurate as you can make it to be.

most accurate will be the digitally calibrated one

Step 3: Prepping the Outdoor Sensors

waterproofing is the key here.

just do enough to extend the life the the sensor but not to hinder their functioning.

Step 4: The Coding

it was written and uploaded using arduino.

choose the file in accordance to the type of circuit you chose.

Step 5: The Housing.

The indoor housing can be anything that allows a little but of airflow to the sensor with ease.

The outdoor housing need not be waterproof since most of the times, 99% waterproof is worse than none (the water could get accumulated into the housing. plus, it'll make the humidity sensor useless. It needs to be transparent to uv, so as to allow the uv sensor to work.

Step 6: UV Sensor Calibration (for Those Who Chose Manual Calibration)​

the formula for output is as follows-


you'll need a friend and a phone with uv sensor for this (I had my samsung s4).

tell him to cover the sensor

turn the variable resistor connected to a3, until the display output reads zero

(for samsung)-to access test mode, dial *#0*#,then navigate to find uv sensor.

tell him to shout the reading that his phone provides,

turn the variable resistor until the reading on both, is the same.

Vola! calibrtion done.

Step 7: FIN,FAQ

Q-Why is the display color red when I've used blue color display?

A-I've replaced the led to match the color of room's furniture

Q-Why haven't I made outdooe sensor, airtight?

A-A homegamer can't airtight properly, so its better to have an opening a the bottom for water to drain out

Q-Where am I getting the power for it from?

A-Power over ethernet, with a transformer in another room