Normally, in an open location, the national weather service (NWS) wind direction would be ok. But as you get into more urban locations, where buildings could change the direction, there is cause for concern. Don't know the answer to this one.
Now for weather stations. There are services available, such as NWS,weather underground, and weather channel, that have stations around that can provide info. More and more of these are charging, instead of being free.
Another option is buying a weather station. These typically run about $150. Some are solar charged. Regardless, they should be put in a high clear location. And regardless of the "solar charging", it's not uncommon for them to need new batteries every couple of trade-off so make sure they are accessable. They usually contact the display by RF ( 433 mhz or 915 mhz are common). Many can also directly access the internet with their data.
There is another option. Check locations near where you plan to put the particle counter. Check for any private weather stations in the area. If it is a school, the data may already be available. But, the other way is to use your computer and an rtlsdr dongle (cost about $20). Using freeware ( with Windows it's sdr# and rtl_433, but there are equivalent versions for linux), you can decode the signals.
See rtl-sdr.com for more details. You will need to spend a fair amount of time getting used to the software. There is also an rtl_433 forum, for more info on that program.