Knoxville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Knoxville clear sky chart from 2005-11-06 to 2024-03-23.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.
Observation TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(no limit)Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
46%
24092
20%
80187
15%
23992
52%
23992
23%
51990

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 10thNight
31%
755
18%
4032
12%
737
41%
737
11%
2650
January11th to 20thNight
26%
758
23%
3971
10%
740
36%
740
11%
2518
January21st to endNight
26%
826
14%
4476
11%
814
39%
814
11%
3053
February1st to 10thNight
31%
760
21%
2299
13%
760
40%
760
21%
1561
February11th to 20thNight
22%
743
16%
2219
8%
740
30%
740
18%
1575
February21st to endNight
24%
628
19%
1884
11%
628
31%
628
18%
1353
March1st to 10thNight
33%
760
21%
2218
12%
760
40%
760
23%
1483
March11th to 20thNight
30%
760
18%
2090
10%
760
35%
760
23%
1452
March21st to endNight
33%
801
17%
2201
10%
801
38%
801
23%
1510
April1st to 10thNight
42%
680
23%
1940
13%
680
50%
680
32%
1155
April11th to 20thNight
39%
533
25%
1753
15%
533
51%
533
28%
1060
April21st to endNight
46%
540
25%
1620
16%
540
53%
540
28%
1032
May1st to 10thNight
49%
540
18%
1620
11%
540
54%
540
28%
1026
May11th to 20thNight
51%
531
15%
1593
10%
531
55%
531
26%
1045
May21st to endNight
57%
582
17%
1744
12%
582
61%
582
26%
1137
June1st to 10thNight
61%
540
16%
1620
13%
540
64%
540
28%
1045
June11th to 20thNight
70%
540
16%
1620
13%
540
72%
540
37%
935
June21st to endNight
67%
540
18%
1620
14%
540
68%
540
29%
1020
July1st to 10thNight
62%
525
11%
1575
9%
525
63%
525
23%
1086
July11th to 20thNight
70%
522
15%
1566
12%
522
71%
522
29%
999
July21st to endNight
68%
591
15%
1672
13%
558
70%
558
28%
1092
August1st to 10thNight
68%
537
16%
1600
15%
534
69%
534
28%
1014
August11th to 20thNight
65%
534
17%
1630
16%
534
66%
534
25%
1091
August21st to endNight
67%
594
18%
1980
19%
594
68%
594
26%
1246
September1st to 10thNight
65%
691
21%
1951
19%
691
66%
691
29%
1268
September11th to 20thNight
60%
720
20%
1980
17%
720
61%
720
26%
1336
September21st to endNight
59%
720
27%
1980
21%
720
63%
720
32%
1241
October1st to 10thNight
58%
720
28%
1980
26%
720
60%
720
36%
1196
October11th to 20thNight
48%
720
27%
2121
22%
720
56%
720
31%
1288
October21st to endNight
50%
792
31%
2386
25%
792
59%
792
32%
1424
November1st to 10thNight
54%
740
27%
2406
26%
740
61%
740
32%
1386
November11th to 20thNight
44%
760
26%
2470
22%
760
52%
760
27%
1481
November21st to endNight
45%
760
25%
2470
20%
760
54%
760
27%
1508
December1st to 10thNight
34%
760
18%
2470
14%
760
41%
760
17%
1732
December11th to 20thNight
37%
759
22%
2972
17%
759
46%
759
18%
1919
December21st to endNight
32%
830
11%
4458
11%
817
41%
817
9%
3073

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

Occurrence of each ForecastData
Points
Cloud CoverDay
13%7%36%6%35%5%6%8%37%
79080
Night
14%7%36%5%35%5%6%7%39%
80820
TransparencyDay
43%6%11%22%15%3
78803
Night
43%6%11%21%16%3
80616
SeeingDay
17%9%21%24%19%9%
13957
Night
17%7%21%32%20%3
24118

By Month

Percentage Cloud Cover SE (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
16%9%46%6%45%6%7%6%29%
2836
11th to 20thDay
18%9%48%7%46%5%5%6%29%
2840
21st to endDay
19%13%47%6%3345%6%31%
3124
February1st to 10thDay
18%10%38%6%34446%35%
1879
11th to 20thDay
22%8%37%6%34346%34%
1848
21st to endDay
20%9%37%5%345%46%34%
1570
March1st to 10thDay
17%8%26%5%3445%6%39%
1962
11th to 20thDay
17%7%47%6%35%45%6%35%
2090
21st to endDay
15%9%47%5%35%5%5%8%34%
2200
April1st to 10thDay
10%5%35%6%46%5%6%8%43%
2034
11th to 20thDay
13%7%25%435%5%5%7%44%
2156
21st to endDay
12%7%36%5%445%6%8%41%
2340
May1st to 10thDay
12%5%36%6%45%5%5%7%42%
2340
11th to 20thDay
11%6%38%7%5%6%5%6%7%36%
2301
21st to endDay
10%6%36%6%46%6%7%10%37%
2531
June1st to 10thDay
9%6%36%6%46%7%7%11%36%
2340
11th to 20thDay
5%425%7%47%6%8%12%40%
2340
21st to endDay
7%436%6%5%7%7%8%11%37%
2340
July1st to 10thDay
8%6%36%7%5%8%7%8%10%31%
2340
11th to 20thDay
10%5%26%7%47%6%8%10%34%
2340
21st to endDay
8%6%37%7%47%7%9%11%30%
2547
August1st to 10thDay
8%6%37%7%5%7%8%9%10%30%
2327
11th to 20thDay
9%6%36%7%46%8%8%11%32%
2267
21st to endDay
9%5%46%7%47%7%7%11%33%
2376
September1st to 10thDay
12%6%347%35%5%5%9%41%
1990
11th to 20thDay
14%6%25%6%445%6%8%39%
1980
21st to endDay
13%6%25%5%2446%7%47%
1980
October1st to 10thDay
10%6%3443445%6%52%
1980
11th to 20thDay
13%5%25%423446%51%
1836
21st to endDay
16%5%245%2445%6%48%
1967
November1st to 10thDay
11%5%24433346%54%
1672
11th to 20thDay
13%5%35%5%2335%7%49%
1710
21st to endDay
14%7%46%425%5%47%43%
1710
December1st to 10thDay
20%9%37%4345%6%7%33%
1710
11th to 20thDay
15%11%27%6%35%5%5%6%34%
2153
21st to endDay
16%12%47%7%35%5%47%29%
3124
January1st to 10thNight
17%11%48%5%3445%6%32%
4109
11th to 20thNight
19%9%36%7%34445%37%
4120
21st to endNight
20%12%46%6%3445%5%31%
4532
February1st to 10thNight
17%9%46%5%35%45%8%36%
2299
11th to 20thNight
22%9%47%5%34445%34%
2218
21st to endNight
22%9%46%445%447%32%
1884
March1st to 10thNight
15%9%47%5%2445%6%39%
2218
11th to 20thNight
17%8%36%5%3445%6%38%
2090
21st to endNight
15%6%47%6%26%5%5%6%38%
2201
April1st to 10thNight
11%4345%3446%8%48%
1940
11th to 20thNight
12%7%25%5%3435%7%46%
1753
21st to endNight
13%5%26%5%45%5%5%7%43%
1620
May1st to 10thNight
12%5%36%5%45%5%7%9%40%
1620
11th to 20thNight
13%7%46%445%5%6%9%38%
1592
21st to endNight
7%5%37%7%36%6%8%11%38%
1744
June1st to 10thNight
6%6%37%6%35%6%8%12%37%
1620
11th to 20thNight
35%245%45%6%8%12%46%
1620
21st to endNight
6%5%36%6%46%6%7%12%40%
1620
July1st to 10thNight
10%6%37%6%5%7%6%9%10%32%
1620
11th to 20thNight
6%5%35%5%46%6%8%12%39%
1620
21st to endNight
6%5%36%7%5%8%7%8%13%34%
1771
August1st to 10thNight
7%5%25%7%45%6%8%10%39%
1611
11th to 20thNight
9%7%48%6%45%7%6%8%38%
1630
21st to endNight
8%6%36%6%45%6%7%10%38%
1980
September1st to 10thNight
10%5%36%5%35%6%6%7%43%
1951
11th to 20thNight
10%8%47%6%45%5%5%7%39%
1980
21st to endNight
10%6%35%5%445%46%48%
1980
October1st to 10thNight
12%6%2443445%6%52%
1980
11th to 20thNight
14%6%25%424446%49%
2121
21st to endNight
13%5%25%5%24345%51%
2386
November1st to 10thNight
13%6%25%423436%51%
2406
11th to 20thNight
14%5%35%5%2445%6%47%
2470
21st to endNight
14%6%35%43445%7%44%
2470
December1st to 10thNight
19%10%37%7%45%35%5%34%
2470
11th to 20thNight
16%9%37%5%3345%7%37%
3042
21st to endNight
17%11%47%7%46%6%6%7%25%
4532

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
51%6%6%24%12%1
2837
11th to 20thDay
54%5%8%19%14%1
2840
21st to endDay
53%5%7%22%13%
3124
February1st to 10thDay
52%48%20%15%1
1879
11th to 20thDay
52%48%20%14%2
1858
21st to endDay
51%48%16%15%5%
1570
March1st to 10thDay
45%48%21%17%5%
1962
11th to 20thDay
49%5%10%19%15%3
2090
21st to endDay
48%6%10%23%12%2
2200
April1st to 10thDay
38%6%10%25%17%3
2034
11th to 20thDay
40%48%18%24%5%
2156
21st to endDay
42%410%27%15%2
2340
May1st to 10thDay
40%7%11%26%14%2
2340
11th to 20thDay
46%6%13%21%12%2
2305
21st to endDay
40%9%14%23%12%2
2531
June1st to 10thDay
40%8%15%23%13%2
2340
11th to 20thDay
35%7%20%22%13%3
2340
21st to endDay
37%11%15%21%12%4
2340
July1st to 10thDay
42%9%17%17%13%1
2275
11th to 20thDay
41%8%19%16%11%5%
2271
21st to endDay
41%10%17%21%10%1
2405
August1st to 10thDay
44%10%18%19%9%1
2314
11th to 20thDay
42%9%17%18%12%2
2267
21st to endDay
43%8%14%19%12%4
2376
September1st to 10thDay
39%7%12%20%16%5%
1990
11th to 20thDay
40%7%12%21%17%3
1980
21st to endDay
36%5%10%23%20%6%
1980
October1st to 10thDay
32%5%9%24%24%5%
1980
11th to 20thDay
34%48%24%24%6%
1836
21st to endDay
36%46%26%23%4
1967
November1st to 10thDay
31%5%7%24%28%5%
1672
11th to 20thDay
36%38%25%24%5%
1710
21st to endDay
41%46%25%20%3
1710
December1st to 10thDay
51%49%23%11%2
1710
11th to 20thDay
49%410%20%15%2
2150
21st to endDay
53%6%8%25%8%1
3124
January1st to 10thNight
51%5%8%20%14%1
4109
11th to 20thNight
50%47%17%19%3
4120
21st to endNight
54%5%6%19%14%1
4532
February1st to 10thNight
48%49%21%16%2
2299
11th to 20thNight
53%47%18%15%4
2219
21st to endNight
54%38%16%15%4
1884
March1st to 10thNight
46%49%17%19%5%
2218
11th to 20thNight
47%410%20%15%3
2090
21st to endNight
46%5%10%24%14%2
2201
April1st to 10thNight
35%412%26%20%3
1940
11th to 20thNight
39%49%20%22%7%
1753
21st to endNight
40%5%10%29%15%2
1620
May1st to 10thNight
38%6%15%24%14%2
1620
11th to 20thNight
41%7%17%22%11%1
1593
21st to endNight
39%9%15%25%11%2
1745
June1st to 10thNight
37%9%16%22%14%2
1620
11th to 20thNight
26%10%23%26%13%2
1620
21st to endNight
36%9%16%22%12%5%
1620
July1st to 10thNight
42%10%17%17%12%2
1575
11th to 20thNight
35%11%20%18%11%5%
1566
21st to endNight
36%11%20%22%10%1
1672
August1st to 10thNight
37%9%20%23%10%1
1600
11th to 20thNight
41%9%16%18%14%1
1630
21st to endNight
39%8%17%23%12%2
1980
September1st to 10thNight
38%8%13%20%17%5%
1951
11th to 20thNight
42%8%11%17%21%1
1980
21st to endNight
36%6%9%22%22%5%
1980
October1st to 10thNight
34%49%21%25%8%
1980
11th to 20thNight
36%5%7%24%22%6%
2121
21st to endNight
35%5%424%26%7%
2386
November1st to 10thNight
35%37%22%25%7%
2406
11th to 20thNight
38%46%22%23%7%
2470
21st to endNight
40%37%27%20%3
2470
December1st to 10thNight
52%49%20%12%2
2470
11th to 20thNight
47%38%22%17%2
3044
21st to endNight
52%8%8%19%11%1
4532

Seeing (when cloud cover <= 80%)
Color Meanings:
Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
23%17%34%20%5%1
270
11th to 20thDay
29%20%30%14%6%1
270
21st to endDay
20%21%36%15%7%
297
February1st to 10thDay
30%16%26%19%9%1
270
11th to 20thDay
34%20%26%17%3
270
21st to endDay
37%17%33%11%3
225
March1st to 10thDay
24%18%29%19%9%2
332
11th to 20thDay
22%17%34%21%7%
460
21st to endDay
23%13%29%26%9%1
470
April1st to 10thDay
18%15%25%26%13%3
420
11th to 20thDay
18%13%28%23%14%4
412
21st to endDay
19%11%27%25%15%3
420
May1st to 10thDay
17%9%32%24%13%5%
423
11th to 20thDay
14%7%26%21%22%10%
447
21st to endDay
15%6%16%24%21%18%
485
June1st to 10thDay
13%5%15%30%24%14%
450
11th to 20thDay
6%5%15%27%30%16%
450
21st to endDay
11%317%28%24%16%
450
July1st to 10thDay
10%312%22%28%25%
445
11th to 20thDay
12%48%27%29%19%
444
21st to endDay
10%38%30%32%18%
488
August1st to 10thDay
15%310%23%29%20%
446
11th to 20thDay
12%29%31%30%15%
439
21st to endDay
13%27%24%29%25%
495
September1st to 10thDay
11%29%24%33%20%
450
11th to 20thDay
15%48%22%32%19%
450
21st to endDay
16%412%28%30%10%
450
October1st to 10thDay
15%7%18%24%25%12%
450
11th to 20thDay
15%11%22%28%20%5%
450
21st to endDay
21%7%21%27%21%2
482
November1st to 10thDay
19%7%24%30%15%4
270
11th to 20thDay
14%11%33%31%9%1
270
21st to endDay
13%10%33%29%14%1
270
December1st to 10thDay
26%17%29%21%6%
270
11th to 20thDay
23%14%29%24%9%1
270
21st to endDay
26%15%28%21%9%1
297
January1st to 10thNight
21%13%26%34%5%
760
11th to 20thNight
26%12%30%27%6%
760
21st to endNight
21%13%33%31%3
836
February1st to 10thNight
21%11%31%34%4
760
11th to 20thNight
27%12%36%23%3
743
21st to endNight
28%12%32%25%3
628
March1st to 10thNight
21%12%28%34%4
760
11th to 20thNight
22%11%32%27%7%1
760
21st to endNight
20%9%29%31%9%
801
April1st to 10thNight
15%10%29%35%10%
680
11th to 20thNight
15%9%31%27%16%1
533
21st to endNight
16%5%27%38%12%1
540
May1st to 10thNight
14%6%23%37%18%2
540
11th to 20thNight
16%5%18%29%26%5%
531
21st to endNight
9%417%27%39%5%
584
June1st to 10thNight
9%313%36%35%4
540
11th to 20thNight
6%313%35%35%9%
540
21st to endNight
7%312%34%37%7%
540
July1st to 10thNight
11%38%26%40%13%
525
11th to 20thNight
7%25%30%46%10%
522
21st to endNight
7%37%31%42%11%
591
August1st to 10thNight
9%46%26%45%11%
537
11th to 20thNight
12%35%30%43%7%
534
21st to endNight
11%26%26%46%9%
594
September1st to 10thNight
11%37%30%41%8%
691
11th to 20thNight
15%48%29%38%7%
720
21st to endNight
13%315%35%31%3
720
October1st to 10thNight
15%6%14%27%32%7%
720
11th to 20thNight
17%6%21%35%18%2
720
21st to endNight
16%5%23%36%19%2
792
November1st to 10thNight
17%5%18%37%21%3
740
11th to 20thNight
16%9%25%37%12%1
760
21st to endNight
18%8%24%37%14%
760
December1st to 10thNight
24%10%25%33%8%
760
11th to 20thNight
21%11%24%35%9%
760
21st to endNight
24%13%22%34%7%
836
Page generated at 2024-03-19 23:31:03. Version ac07

Copyright © 2024 Attilla Danko.


Knoxville Clear Sky Chart |Charts Home