The Austrian forward joined the Rams from Aston Villa in the summer of 2015, but despite predominantly being a forward, he has often featured out on the wing.
Weimann has struggled to score goals and create assists during his time at Pride Park, but supporters have appreciated his non-stop running and the 100% effort he consistently puts in.
Bristol City are seemingly looking for reinforcements this summer with several key players linked with an exit, and Weimann could be considered a potential replacement for coveted striker Bobby Reid.
The report in the Daily Star claims a fee has been agreed for the player, with Derby boss Lampard happy to sanction a deal as he looks to reshape his squad for the coming season.
It has been suggested that the Rams may have to sell first before buying this summer as they edge close to the Financial Fair Play limit, though many expected top scorer Matej Vydra would be the first out the door.
Derby are seemingly paying the price for overspending in their bid to earn promotion to the Premier League, and Weimann’s potential exit will leave them fairly short in attacking wide options.
The 26-year-old has made a total of 77 league appearances for the east Midlands club, scoring a total of nine goals.
If Lampard is keen to implement a new possession-based style at the club, then allowing Weimann to join the Robins makes plenty of sense with the player far more suited to a counterattacking system.