nectarine species [+/-]
Enviroment
Without spraying regularly, nectarines are more difficult to grow in wet climates than peaches. The combination of excessive moisture and their lack of fuzz causes them to be more vulnerable to bacterial, fungal, and insect damage. They are also more prone to cracking than peaches.

Nectarine trees can survive down to zone 5a (-15 to -20F) or lower, but their flower buds are only hardy down to roughly -5F to -12F, depending on the weather of the previous few days. Bud hardiness begins around -5F, but they develop a few extra degrees of hardiness, down to -12F, for every day the temperature is below 29F. If the temperature rises above freezing once again, even for just a few hours, the process restarts. Some of the more cold hardy cultivars, typically the later blooming ones, have fruited after experiencing zone 5a/4b temperatures (-18F to -23F), so they are capable of achieving bud hardiness much greater than -12F.
Pollination
self-fertile
Soil
Prefers slightly acidic soil (6.1 - 6.5). Intolerant of saline soil.
Other
Some nurseries list most of their nectarines as being hardy down to zone 6, but a few others have the same cultivars listed as zone 5. This is probably because their buds are hardy down to 6b by default, but some nurseries take advantage of the fact that they can develop increased hardiness during the winter, as mentioned in the environment section, and the tree itself can survive down to zone 5. Which zone is more appropriate depends entirely on the climate since some zone 5 areas are more suitable than others.

Blossom damage from spring frost is a fairly common issue throughout much of the US, although I'm under the impression that most areas still end up producing fruit more often than not. You can help avoid this problem by planting late blooming cultivars.

Peach leaf curl is a problem in areas that experience cool and wet winter or spring conditions. This is why many cultivars are harder to grow in the Willamette Valley as well as much of the Eastern half of the US. If you do not plan on spraying to keep the disease at bay, aim for resistant cultivars. This is far from being a perfect solution though, I believe "very resistant" cultivars aren't even close to being immune, so you may continue have problems with the disease. You can still get nectarines if you let peach leaf curl do its thing, the tree just won't be as productive as it could be.
Additional Reading
Evaluation of Nectarine Cultivars in Northern and Southern Mississippi

Nectarine
Prunus persica

Artic Glo

Zone
:
5? (6)
Chill Hours
:
400-500
Stone
:
clingstone
Color
:
white flesh

Atomic Red

Zone
:
6?
Chill Hours
:
500
Color
:
white flesh

Atomic Red produces double petal flowers.

Fantasia

Zone
:
6? (5)
Ripens
:
Mid to Mid-Late?
Chill Hours
:
500
Stone
:
freestone
Color
:
yellow flesh
Afflictions
:
Susceptible to bacterial spot.

Flavortop

Zone
:
6?
Ripens
:
Mid
Chill Hours
:
600-850
Stone
:
freestone
Color
:
yellow flesh

Goldmine

Zone
:
5? (6)
Blooms
:
Late?
Chill Hours
:
400
Stone
:
freestone
Color
:
white flesh

Hardired

Zone
:
5
Blooms
:
Late?
Ripens
:
Mid-Late
Chill Hours
:
850
Stone
:
semi-freestone
Color
:
yellow flesh
Afflictions
:
Resistant to bacterial spot.

Hardired is the second most recommended cultivar for colder climates, right after Mericrest.

Harko

Zone
:
5? (6)
Blooms
:
Late?
Ripens
:
Early-Mid?
Chill Hours
:
800
Stone
:
semi-freestone
Color
:
yellow flesh
Afflictions
:
Resistant to brown rot and bacterial spot.

Independence

Zone
:
5? (6)
Chill Hours
:
700
Stone
:
freestone
Color
:
yellow flesh

Juneglo

Zone
:
5? (6)
Ripens
:
Early
Chill Hours
:
700
Stone
:
semi-freestone or clingstone
Color
:
yellow flesh?
Afflictions
:
Susceptible to brown rot.

Precocious?

Kreibich

Zone
:
5? (6)
Chill Hours
:
800
Stone
:
freestone
Color
:
white flesh
Afflictions
:
Has some resistance to peach leaf curl. May also have some resistance to bacterial canker.

Mericrest

Zone
:
5
Blooms
:
Late
Ripens
:
Mid?
Chill Hours
:
800
Stone
:
freestone
Color
:
yellow flesh

Mericrest is one of the most promising nectarine cultivars for zone 5 winters and late spring frosts. It is often mentioned for having a very good flavor too.

Necta Zee

Zone
:
6?
Chill Hours
:
400
Stone
:
freestone
Color
:
yellow flesh

Necta Zee is a mini tree that can be maintained around 6ft in height.

Pacific Pride

Zone
:
6? (5)
Color
:
white flesh
Afflictions
:
Has some resistance to peach leaf curl

Pacific Pride ripens roughly 2 weeks after its parent 'Kreibich'.

Redgold

Zone
:
5? (6)
Blooms
:
Blossoms may have some additional resistance to spring frosts.
Ripens
:
Mid
Stone
:
freestone
Color
:
yellow flesh

Royal Giant

Zone
:
5? (6)
Ripens
:
Late to Very Late
Stone
:
clingstone
Color
:
yellow flesh
Afflictions
:
Susceptible to brown rot.

Snow Queen

Zone
:
6?
Chill Hours
:
250-300
Stone
:
freestone
Color
:
white flesh

Southern Belle

Zone
:
7?
Blooms
:
Early
Chill Hours
:
300
Stone
:
freestone
Color
:
yellow flesh

Southern Belle is a dwarf tree that grows up to roughly 5ft tall.

Sunglo

Zone
:
5? (6)
Ripens
:
Early-Mid to Mid
Stone
:
freestone?
Color
:
yellow flesh
Afflictions
:
Susceptible to bacterial spot.