Dr Cliff Arnall, a former Cardiff University lecturer, has revealed that June 18 is the happiest day of this year.

“Around 20 million people will watch England v Algeria on TV, and a win would mean millions being on a high even higher than is seen among most people at this time of year,” The Daily Express quoted Dr Arnall as saying. “The third Friday in June came out with the highest rating due to peaking happiness factors such as warm summer evenings outdoors, seeing friends more frequently, and excitement about holidays."
The happiness formula calculates being outdoors (O) and adds it to nature (N). This sum is multiplied by social interaction (S) and is added to childhood summer memories (Cpm) divided by temperature (T). This value is then added to holiday excitement (He) to produce the happiest day of the year.
Source-Medindia