The U.S. Independence Day long weekend is typically a big moneymaker for Hollywood studios, with bored holidaymakers eager to open their wallets for a little summertime distraction.

But this July Fourth long weekend went off like a a soggy firecracker.

Ticket sales at North American theatres were down 44 per cent from the same weekend a year ago with three new movies raking in just $61.4 million (all figures in U.S. dollars.)

Transformers: Age of Extinction had the year's biggest opening weekend a week ago with $100 million in sales, but it grossed just $36 million this weekend, representing a disappointing 63 per cent drop.

The new comedy Tammy, starring the highly bankable Melissa McCarthy, also under performed with a weaker than expected haul of $21.2-million.

Melissa McCarthy and Susan Sarandon

Melissa McCarthy's Tammy which earned $21 million in its opening weekend.

Eric Bana's horror flick Deliver Us From Evil came in a distant third with $9.5 million.

Analysts cite a variety of reasons for sluggish box office sales including the fact that the Fourth of July fell on a Friday this year and there has been a lack of family friendly summer blockbusters.

Some studios may have also opted to hold back their bigger releases until the end of World Cup.

Whatever is causing the slump, 20th Century Fox is likely hoping Dawn of the Planet of the Apes will swing in and save the summer.

The big-budget action re-boot opens Friday starring Gary Oldman, Keri Russell, Jason Clarke, and Andy Serkis.