While the board is in manufacturing, mill the enclosure for the display & switch.  If you will be using the enclosure listed in the parts list, cutout dimensions are included in the files section.  You'll want to have this done before assembling the board because the LCD & switch will need to stand-off the PCB a bit to mount flush (LCD) and protrude (switch).

U1 will be mounted on the end of multi-wire cable that will be positioned outside to sense air temperature.  The cable should be thin in diameter so it doesn't interfere with closing the window and won't be damaged.  Individual wires in the bundle can be 28AWG or smaller.  A shield isn't necessary unless the sensor will be located close to an electrical noise source.  I used an old USB cable.  The cable shouldn't be much longer than 1 meter (3 ft.).

One end of the cable will be soldered directly to the PCB; the opposite to the temp sensor leads.  Each lead on the sensor should be protected with heat shrink tubing and then the entire sensor head enclosed in tubing as well.  The tip & base seams of the heat shrink tubing should be sealed with silicone or RTV to prevent moisture from seeping in.  See the project pictures for reference.

Suggestion:  unlike my photos the sensor will be less prone to error in direct sunlight if white or reflective tubing is used to protect it.

The PCB accommodates in-circuit programming - this is what jumpers JP1 & 2 are for.  So if you have the proper cabling to connect the programmer to the installed PIC you can skip this step; otherwise program the PIC now before soldering to the PCB.

Start with the resistor & caps first.  Then the PIC.  The LCD & switch go next.  Before soldering them they should be set in the PCB and fitted with the enclosure to ensure that the cutout is correct and that they are soldered at the correct stand-off height.

Solder a jumper across JP3, (PWR).  I had included this to connect an amp meter to measure current draw.

Now is a good time to program the PIC:  power the unit with your bench supply (3V) or directly from the PICkit3 programmer.  When complete & still powered up the unit will display a random temperature since the sensor isn't connected.  Note that the two segments driven by the ICSPDAT & ICSPCLK pins won't work until jumpers JP1 & 2 are installed.  If you want to verify it's working properly you can apply 0.5V to the 'Tsense' pad and 0C (32F) should display.

If not done, solder jumpers across JP1 (ICSPDAT) and JP2 (ICSPCLK).  Install the battery clips.

The temperature sensor cable should be connected last.  You'll want to fashion some sort of strain relief:  I tied a knot in the cable.  Also be sure to place a notch in the enclosure for the cable.

Install batteries and it should be up & running.  Be sure to check temperature response and that it's displaying / switching units (C / F) properly.  Note that the display only updates every eight seconds so depending on timing it may not respond to the switch or temp change immediately.

There's plenty of gap in the enclosure where the display & switch protrude that will allow dust & dirt in.  Plus, I'm not the best at hand routing so the enclosure cut was a bit ragged.

I wound up printing a simple label and covering with laminate.

Install and enjoy.