Donation centres around the country have seen donations drop significantly on England's match days, with Saturday's nail-biting quarter final game against Sweden seeing a drop as high as 20 per cent.
On warm weather days, blood donations have often been between five and 10 per cent down on what was forecast.
The combined effect has cost the NHS around 2,000 blood donations over the last two weeks, leaving an urgent need for people with the valuable O negative group to donate in the next few days.
NHS Blood and Transplant are urgently appealing for support to ensure hospital patients get the O negative blood they need.
Mike Stredder, director of blood donation for NHS Blood and Transplant, said: “The long spell of sunshine has been great in many ways, but some people have chosen to stay in the sun instead of giving blood, and some people haven’t been hydrated enough to donate safely.
“England’s excellent World Cup has also meant football fans are spending their time enjoying the games rather than donating blood.
“However, hospital patients urgently need blood every day of the year, whatever the weather."
NHS Blood and Transplant normally aim to have six days worth of blood stocks, but the recent heatwave and World Cup excitment has seen these levels fall to just three days work of O negative blood.
This blood group is especially important as it is the universal donor group which can be given to almost any individual in an emergency, making the specific O negative appeal especially urgent.
NHS Blood and Transplant is asking O negative donors to book an appointment, or to walk into a donor centre and donate.
Donors are to make sure they are well hydrated on the day of donation and are asked to give 72 hours notice if they need to cancel.
If you are O negative and you can donate, call the Leeds City Blood Donor Centre on 0300 123 23 23 to make an appointment, or book an appointment here.