At this time, Cheapflights has noticed price decreases for many domestic flights due to COVID-19. Travel is not necessarily recommended at this time, and flights may be prone to cancellation: please check with local authorities in both Oxford and London for travel alerts, and be sure to review the airline's cancellation policy and travel advisories before booking. For more information, please view our post on what to know about COVID-19 (coronavirus) and travel.
You can imagine temperatures to be in the 23 °C range in July. The weather in London is generally the same as Oxford's. As flight availability is subject to become more limited as peak season approaches it is ideal to book in a timely manner.