This post was inspired by an article posted on r/boxoffice which was asking if whether we are entering an era of year-round blockbusters. 2019 will have at least one film every month that has a good chance of passing $300 million worldwide, which may prove the article correct. For a film with a budget of $100 million or less, $300 million worldwide would be a great success, for those not well-versed in box office, and almost every film besides Marvel, DC, Star Wars or other big blockbusters have a budget under $100m. Obviously some months will have far more than others but nonetheless, it can still happen.
January
-
Ad Astra (Brad Pitt and Tommy Lee Jones space movie)
-
Hellboy (with David Harbour)
-
Spies in Disguise (animated film with Will Smith and Tom Holland voicing spy pigeons...)
-
Glass (sequel to Unbreakable and Split)
February
-
The Lego Movie Sequel
-
Silver & Black (Sony Marvel Spider-Man spin-off focusing on Silver Sable and Black Cat)
March
-
Chaos Walking (YA film with Tom Holland and Daisy Ridley along with Doug Liman directing)
-
How to Train Your Dragon 3
-
Captain Marvel
-
Godzilla: King of the Monsters
-
Dumbo (Disney live action film with Tim Burton directing)
April
-
Shazam! (DC Superhero movie)
-
The Voyage of Dr. Dolittle (starring Robert Downey Junior)
May
-
Avengers: Infinity War Sequel
-
Detective Pikachu (with Ryan Reynolds)
-
John Wick: Chapter 3
-
Aladdin
June
-
The Secret Life of Pets 2
-
Men In Black 4
-
Toy Story 4
-
Transformers 6
-
Cowboy Ninja Viking (with Chris Pratt)
July
-
Spider-Man: Homecoming sequel
-
Top Gun: Maverick (with Tom Cruise)
-
The Lion King
-
Hobbs and Shaw
-
Terminator 6 (with Arnold Schwarznegger and Linda Hamilton returning)
August
-
Artemis Fowl
-
Manson Murders Film (Quentin Tarantino and Leonardo Di Caprio)
September
-
It: Chapter Two
-
The Angry Birds Sequel
October
- Gemini Man (Sci-Fi Action flick with Ang Lee directing and starring Will Smith)
November
-
Wonder Woman 2
-
James Bond 25 (Daniel Craig supposedly returning)
-
Frozen 2
December
- Star Wars: Episode 9
The months with some people may have some doubts I'd say is January, August and October and I would agree to an extent. Glass in January should easily be able to pass $300 and so should Quentin Tarantino's August film but Gemini Man with October may seem unlikely. However, an sci-fi action film with an Academy Award Winning Director and one of the most recognisable actors, should be able to clear $300 million.
Edit: Wrote 'Avengers: Infinity War' instead of 'Avengers: Infinity War Sequel'. Also, I accidentally added 'Solo: A Star Wars Story'
Edit #2: Added a couple more films based on suggestions from the comments