You know that wifi under 10.8.4 on the newest MacBook Air are also an issue?
If you cannot connect , then you cannot download drivers and updates from inside Windows to get 8.1 security updates and others.
Can you and do you have ethernet to Thunderbolt adapter ? that way you can establish and setup Networking settings first wired which often is best route.
(Google really is a great place to start with)
How many routers? all current? needing firmware updates?
Apple? other brands?
Go to Settings > Control Panel > Device Manager. Then choose your WiFi Network Adapter. Choose Install Drivers > Browse my computer for driver software > Let me pick from a list of device drivers on my computer. Then scroll down to "Broadcom" and choose "Broadcom 802.11ac Network Adapter". Click Next and grand permission to install. After installation reboot your MacBook.