Please be aware that Shanghai has multiple airports and that these results are for all airports serving the city.
The best month to fly between Shanghai and Guangzhou is March and the most expensive month to fly is June. (Average prices, based on 396 datapoints.)
The best day to arrive at Shanghai is Monday and it would be best to avoid Saturday, as prices are on average 84.1% higher than on Monday. (Average prices, based on 263 datapoints.)