The issue for the southern AT is elevation.
Temperatures drop about 5.4 degrees F per 1000 ft. The trail elevation in the north half of PA never exceeds 1600'. The first shelter above 1600' is Riga Shelter (mile 1510) and above 2000' is at Mt Wilcox (mile 1541) just before Upper Upper Goose Pond Cabin in northern MA. These elevations are from the WhiteBlaze Shelter list. Springer Mountain Shelter sits at 3730' while the rest vary between 3000' and 4900' until you get to the Smokies (except two). The shelters in the Smokies range from 1175' (Fontana Hilton) to 5900'. Clingman's Dome (mile 201) is the highest point on the trail at 6643'. Roan High Knob shelter (mile 379), north of the Smokies is the highest shelter on the trail at 6285'.
Listed below are the
mean low,
25 percentile, and
10 percentile temps (F) in
Gatlinburg (1039') for May 1, June 1, and July 1 and estimated temps adjusted for altitude. Some seem on the low but its give general picture.
Mean Low temp by elevation based on Gatlinburg |
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temp (F) |
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elev ft |
1-May |
1-Jun |
1-Jul |
|
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1039 |
49 |
58 |
64 |
|
|
|
|
|
2000 |
43.8 |
52.8 |
58.8 |
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|
|
3000 |
38.4 |
47.4 |
53.4 |
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|
|
4000 |
33.0 |
42.0 |
48.0 |
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|
|
|
|
5000 |
27.6 |
36.6 |
42.6 |
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|
|
|
6000 |
22.2 |
31.2 |
37.2 |
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25% of day temps will be at or below this temp. |
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temp (F) |
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|
elev ft |
1-May |
1-Jun |
1-Jul |
|
|
|
|
|
1039 |
44.0 |
54.0 |
62.0 |
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|
|
|
|
2000 |
38.8 |
48.8 |
56.8 |
|
|
|
|
|
3000 |
33.4 |
43.4 |
51.4 |
|
|
|
|
|
4000 |
28.0 |
38.0 |
46.0 |
|
|
|
|
|
5000 |
22.6 |
32.6 |
40.6 |
|
|
|
|
|
6000 |
17.2 |
27.2 |
35.2 |
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10% of days temp will be at or below these values |
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temp (F) |
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|
|
elev ft |
1-May |
1-Jun |
1-Jul |
|
|
|
|
|
1039 |
38.0 |
49.0 |
57.0 |
|
|
|
|
|
2000 |
32.8 |
43.8 |
51.8 |
|
|
|
|
|
3000 |
27.4 |
38.4 |
46.4 |
|
|
|
|
|
4000 |
22.0 |
33.0 |
41.0 |
|
|
|
|
|
5000 |
16.6 |
27.6 |
35.6 |
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6000 |
11.2 |
22.2 |
30.2 |
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Gatlinburg temp map. Note that the variation in temperature narrows as you head toward summer and from another graph
https://weatherspark.com/s/16309/1/A...es-Temperature
Elevation profile (Postholer.com) from about MD/PA line (mile 1070) to Hwy 9 (Bennington mile 1612) and for the trail
Attachment 50251
Attachment 50252
Finally be aware that it is 1.2 to 1.4 times more likely to rain in Gatlinburg than Allentown. Think cold rain. Damp bag.