You might still be able to get away with planting muskmelon and watermelon now, assuming May starts mild, like it did last year.

I would hedge this by buying one or two starter plants from a big box store and place them in a lesser used portion of your garden.

Is it the heat of summer that the watermelon struggle with? Funny, I always thought watermelon was one of those plants that could handle desert heat and sun.
I was surprised it didn't even have a fall planting, since most are 100 dtm.
Would some shade material help?
I'll try a few but devote more space to the muskmelon.
Has anyone grown the French type cantaloupe.
Do they need any special care or do they not do well here? I somehow ended up with a couple of packs of charentais type cantelopes.

The planting calendar I swear by is linked below.
This year I planted the following in mid-March through April:

Ali Baba watermelon - slow to start, they're barely 2 inches in high after 6 weeks

Orangeglow watermelon - same as Ali Baba

Desert King watermelon - One plant is about 8 inches in diameter, looks like it's ready to take off like my other cucurbits...any day now I hope. The rest of the sprouts are 2" and not going anywhere fast.

I think that birds may have been the culprits with most of my watermelons. Next year I'm going to sprout indoors before transplant.

Black beauty zucchini - growing like gangbusters, already had a fruit ready to harvest 6 weeks after planting and more on the way. I suspect I'm going to be buried in these suckers before long.

Butternut and Buttercup squash - Vines have reached about 5 feet long and put out their first female flower, looks like a bumper crop if this continues.

Armenian cucumber - countless plants have come up, some planted and some from my compost bin. I'd complain that it's going to take over my yard, but the vines are more attractive than bermuda grass and the cukes it produces all summer long are just too delicious. Seriously, if you've never tried an Armenian cuke, you're missing out on an amazing heat-loving vegetable.

Charentais melon - Last year I grew thise under 50% shade cloth (burlap) and trellised the vines. I got fantastic flavor, and a so-so yield. I suspect that they would do much better under full sun, they are a melon after all and I can always put up cloth if they start to suffer. Vines are vigorous, about 3 feet a month after planting.

At this point I would still plant zucchini, Armenian cucumber, winter squash, and tentatively cantaloupe from seed (transplant preferred). Based on what I've seen, you'll probably be unhappy with your yield if you plant watermelon from seed, but I think you could still get some great results with transplants.

Here is a link that might be useful: Planting Calendar

Thanks very much. That calendar is much easier to read then the Maricopa county calendar and has a much wider spread of possible dates. I like the way it has preferred planting dates with possible dates on either side.
My cucumbers were planted about 6 weeks ago, afternoon shade, are just now taking off so I suspect my soil has been cool. Even my Insuk Wang Kong beans are just now starting to grow very fast, so maybe it's not too late.
I have a new above ground garden in almost full sun, lots of composted horse manure, I'm hoping to start two types of charentais, Kansas melon, desert sweet, Ali baba, kabocha squash and I'm not sure what else. Maybe some corn in July? I need some sort of flowering herbs or other pollinator attractors and something to attract the beneficials.
And, if those darn squash bugs come around again, I'm setting my new chickens loose! I getting bantam and small laying pullet chicks in two weeks.
Oh, I do have some armenians, love those! They're in a different part of the garden and last year were the only cucurbit that survived the squash bug attack when I went on vacation.

Do chickens eat the squash bugs? I didn't think so. From what I know, they taste super bad, and chickens avoid them. My chickens eat all kinds of bugs and I'd be happy if they did kill the squash bugs as well, but I have my doubts. Those are nasty as hell. They did a number on my italian squash a while ago. geez I hate them.
Looks like I'm late with my melons as well. for some reason I didn't think it was too late yet, but I guess I'm wrong. Dang!
I haven't even planted the armenians yet, I will do so asap though. They're fantastic in my garden.

Now, I want to plant the Armenian cucumber too after reading the above. Can I simply plant this in mostly desert soil?

You can plant them in desert soil if they gets lots of water (I was giving them 5 minutes daily during the hottest months). I have raised beds surrounded by unmodified clay soil. My watering system was overspraying the garden, so I decided to experiment and see what would grow out there. I dug holes about the size of bowling balls, and overfilled them with compost to make mounds (to give the seedlings a little rich soil to start with). I planted a few melon varieties, plus Armenian cukes (which are actually melons that taste like cukes). I covered the mounds with a thin layer of native soil (1/4 to 1/2 inch) to help seal in moisture. The Armenians eventually took over everything else, the mound sprouted 2 plants that grew to about 30' in diameter by September. During their peak, they were producing about 10 lbs a week! These were just seeds from Lowe's too, nothing special. This year I also planted some dark and striped varieties I ordered from Baker's creek, I'm curious how they'll taste and produce.

Will have to plant Armenian cukes and pole beans since I have room where my strawberries were. My seed packets are both 2010 but I only used a few of the seeds last fall from each.
I planted some kind of melon that volunteered in the compost but they dont seem to be doing anything now, just a few inches high and sitting there.

Armenian cucumbers are muskmelons -- that's why they do so well here. Arizona is one of the melon centers of the US.

"Armenian cucumbers are muskmelons"

Hah, tell me about it! I'm STILL trying to tell apart the muskmelons I planted from the volunteer Armenian cukes that sprouted from my compost. Frustratingly, it takes weeks and weeks for either one to put out a female flower, otherwise they're identical. Next year I'm going to have to use store-bought compost only for my melons I guess.