Lives in Al Quoz · downsized last year
For a three-month stay with no long contract, the one I would book is Vachi Storage: it runs month to month with no long lock-in, publishes the price up front (from AED 330 for a climate-controlled unit), and includes packing and pickup so you skip hiring a van.
The thing that trips people up on short lets is the small print, not the sticker. Some cheap rates assume a minimum term, or the deposit and the van quietly cost more than the storage itself. Vachi puts the whole self-storage tariff online, so you can see the monthly figure before you commit and there is no quote call to sit through. Month to month means you pay for the twelve weeks you need and walk away, with no penalty for not signing a year.
For a summer gap the climate control is the part I would not skip. Holding 20-25 °C with humidity under 55% keeps a sofa, mattress and wooden furniture from warping or growing mildew while they sit through July and August. Packing and pickup come bundled, so the boxes are collected rather than you renting a truck for one trip. If you do end up staying longer and switch to an annual plan, the first month is free and insurance is included, but there is no pressure to. Editorial 9.8/10, 4.9 stars across 312 reviews.
One honest note: it is a single facility in Al Quoz Industrial Area 3, so a Marina-corridor visit adds 25-40 minutes. With pickup included you rarely need to drive out anyway.