Consumer Reports: Lots of sales! But what should you buy in May?

PHILADELPHIA (WPVI) -- With Memorial Day right around the corner, May is a month with lots of sales and deals to be had - you just need to know where to find them.

Consumer Reports tracked the prices of many of its top tested products all year long, so they know exactly when they go on deep discount.

Here is its roundup of great deals.

In this month's "Best Time to Buy", mattresses are at the top of the list.

"With mattresses, we tend to see sales on them all year long. You should never, ever pay full price for a mattress - that's how frequent the sales are. But during these bigger sales moments like Memorial Day, we tend to see larger discounts," said Consumer Reports shopping editor Samantha Gordon.

CR found a queen-sized Tuft & Needle Original Mattress for $590 at Tuft & Needle. That sale started on May 10.

CR's tests show that Tuft & Needle makes good mattresses all-around.

If your home office is starting to get a little stuffy and it can't accommodate a window air conditioner, opt for a portable one.

Check out the Whynter Portable Air Conditioner for $570 at Amazon.

CR says that model is among the best portable air conditioners they've tested.

And still need a belated Mother's Day gift? Why not get mom some new tech gear!

CR found a Samsung Galaxy Active2 Smartwatch for $180 at Amazon, Best Buy, and Walmart.

May is also a great month to find deals on blenders. The Nutri Ninja Personal Blender is $50 at Walmart.

That model scores very well for smoothies in CR's tests.

And finally, some advice on taking advantage of those big Memorial Day sales:

"Around mid-May, you'll start to see these sales really start to pick up, but the deals may be better the closer you get to Memorial Day," said Gordon.

These deals can go quickly, so take advantage of any sales early, especially on popular products.

Note: Consumer Reports is an independent, non-profit organization that buys everything it tests. CR has no financial relationship with any manufacturers or products featured in this report.