Ginkgo biloba 'Princeton Sentry' is columnar and very adaptable. The more you water them, the faster they will grow.Most deciduous trees are not very heat- and drought-tolerant, although the NW native oaks can take it.

Since the space is so narrow, have you thought about a climber? If this is a possibility, I'm sure you would have more choices and the experts here would have suggestions. One thought I have is a fremontadendron. I love the cheery yellow flowers.

Space not very adequate for anything tall enough to be considered a tree. Then there is the matter of whether or not 20' beanpoles will cast big enough shadows to do the job - after you have waited years for them to develop. How long are you willing to wait? You probably really need an architectural solution or other modification to the structure - maybe air conditioning.

I see those columnar hornbeans planted all over. They use them in narrow parking strips along the sidewalks and in parking lots. Their foliage is very dense. I assume they are drought tolerant since they are being planted in hot dry situations.

The one seen all over is Carpinus betulus 'Fastigiata' which bulges out into an egg shape as it develops. Like many other kinds of trees planted on streets in this region it actually doesn't appear to enjoy the often poor dry soils of streets with many examples not developing as vigorously as they would on better sites; sooty mold fungus from sucking pest infestations (perhaps aphids) are also prevalent in summer among columnar hornbeam street tree plantings I pass by here. Insects like these may be attracted to distressed specimens particularly.

Alternative cultivar 'Frans Fontaine' is beginning to appear in plantings here and is supposed to remain narrow. However, even this one will grow far too large for the situation described. The parent species is a full-sized tree growing 60' high or more on suitable sites.