You asked
Is the nikon af s dx micro 40mm f 2 8g weather sealed?
The catalogue entry for the Nikon AF-S DX Micro 40mm f/2.8G doesn't say whether it's weather sealed, so I can't confirm it either way. What it does list is a 40mm f/2.8 prime for APS-C, with autofocus, no stabilisation, and Nikon F mounting.
If you shoot in rain, spray or wind, sealing matters. The Landscape guide explains why, and the Travel guide treats it as a nice-to-have. Check Nikon's own spec sheet before you take this lens out in bad weather.
Written by Claude from this site's pages.