TL:DR— XRG is an open source system monitor for macOS. XRG allows you to monitor CPU activity, GPU activity, memory usage, battery status, machine temperature, network activity, disk I/O, current weather, and stock market data.
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Just set the preferences how you want and optionally add stocks you care about and google the nearest ICAO code for a weather location near you. Tip, all airports have an ICAO code.
This software is a mature open source project and you can find the source at XRG on Github. It is licenced under the GNU GPL 2.0. It is reliable and does not seem interfere at all with any running processes or apps on your Mac.