ESP8266 - Which mode to use?

I'm setting up a temperature/humidity sensor in my garage.

I want the device to send the data to a local server that will log ongoing data into a database.

I also want to be able to log in from my cellphone from outside the local network and check the temp and humidity.

Will I need to set the ESP8266 to Station Mode, AP mode, or BOTH Mode?

If I set it to STA (Station mode), then it will connect to my existing network. Since the ESP8266 has no security built in, isn't that opening a portal for anyone to access my network?

If I set it to AP mode, how would I transmit the data from the device to my local network and access it from outside the local network?

I think I would have to set it to STA mode....is that correct?

Thanks

I would look at the ESP8266 ESP-12E.
https://www.ebay.com/itm/NodeMCU-ESP-12E-ESP8266-WiFi-LUA-IoT-CH340G-V3-New-Version-Arduino-Compatible/32238992374w

You don't even need an Arduino.

noiasca:
yes, you will need STA mode.
The ESP supports WPA-PSK ... so it is per se not unsafer than any other device in your WIFI LAN ...

ESP8266 supports WPA-PSK ? Cool.
Learn something new every day. That changes things a bit

Thanks