We are looking to start a Storm King's Thunder campaign, but I'm trying to figure out when in the timeline the campaign takes place relative to Rise of Tiamat. Are there any references that state this?
In The Storm Kings Thunder, in the Adventure Background section it states that the Rise of Tiamat has occured previously and that the area is recovering from the events in that module.
I am unaware of any specifics about timings but I assume the idea is to be vague so that DMs can decide to suit their campaigns.
Generally speaking, hardcover adventure modules do not have specific time cues in them. This is a deliberate game design choice that allows a DM to work the product into their own campaign however they'd like.1
If you want the "official" order, you need to look to a different officially published WotC product - the D&D Adventurer's League, their organized play engine...
Each Adventurer's League season corresponds to a hardcover adventure book release, and the seasons themselves make references to prior seasons - establishing a sequence. However, there are not hard time cues to nail each season down to specific Dale Reckoning years, just the sequence.
For example, DDAL Season 2 modules make reference to refugees from Phlan, who fled during DDAL Season 1. Season 2 ties to Princes of the Apocalypse, while Season 1 ties to Rise of Tiamat. Therefore, Tiamat takes place before Princes.
So, the in-world sequence of the published adventures is the real-world publishing order, but the exact spacing between them is nebulous - there is a sequential order, but not a contiguous one. WotC has no way to determine exactly how much character-calendar time each party will spend on an adventure, so there's no way (and no reason) to be more specific than a general order - "these events happened before those events".
1It should go without stating that a DM can change whatever they'd like, including time references, but citing "DM's prerogative" in every answer is a waste of time. The DM can almost always do whatever they like, all the players can do is walk away.
- Tyranny of Dragons happens first.
- Elemental Evil happens next.
- Ghosts of Dragonspear Castle, Murder in Baldur's Gate and Lost Mines of Phandelver predate both. (These events happen in this respective order)
- 1st part of Out of the Abyss happens during RoT, 2nd part during EE.
- Storm King's Thunder takes place after OotA.