But I read many people saying sd card is weak link.
It is one of the few weaknesses of the Pi that it doesn't have a better interface to storage devices and so you only have 3 storage options: An SD card; a USB device like a USB stick, but could also be eg a USB SSD or hard drive; or storage across the LAN somewhere.
The problem with consumer SD cards and USB sticks is that they tend to use TLC NAND memory these days, which give good value for large capacity but do have limited life if used in applications where there's constant writing of data to the card/stick. There is a solution which is the use of so-called industrial or military cards or USB sticks, which use SLC (single cell) NAND memory but these are relatively expensive, eg:
https://uk.rs-online.com/web/p/usb-flash-drives/7761945/One configuration of the Pi which should work reasonably reliably is still to use an SD card as the boot device (but where it won't constantly be written back to) but use eg an industrial USB stick for storage of weather data. Although 2GB doesn't sound like much storage (except to old-timers
) it probably will go a long way for storing the relatively modest quantities of weather data that are generated. I don't know for sure whether weewx supports this configuration, but I'm pretty sure that it would.
Of course, it's always sensible to back up data, whatever medium it's stored on.