This page made possible by the sponsorship of: Mark Manner.

Nashville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Nashville clear sky chart from 2005-11-06 to 2024-01-16.

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
45%
23841
22%
74309
16%
23785
52%
23785
26%
46867

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
26%
950
19%
2648
9%
946
35%
946
22%
1810
January11th to 20thNight
22%
856
17%
2521
8%
856
31%
856
15%
1851
January21st to endNight
26%
792
22%
2403
10%
792
38%
792
22%
1599
February1st to 10thNight
25%
720
17%
2160
9%
720
32%
720
17%
1561
February11th to 20thNight
21%
703
18%
2099
9%
700
29%
700
18%
1474
February21st to endNight
19%
592
18%
1776
8%
592
27%
592
16%
1284
March1st to 10thNight
30%
720
19%
2160
9%
720
38%
720
22%
1422
March11th to 20thNight
29%
720
18%
2070
10%
720
36%
720
21%
1434
March21st to endNight
33%
684
19%
2070
12%
684
40%
684
22%
1372
April1st to 10thNight
37%
540
26%
1800
15%
540
52%
540
29%
1043
April11th to 20thNight
36%
533
27%
1775
17%
533
50%
533
28%
1035
April21st to endNight
38%
540
23%
1764
14%
540
50%
540
27%
1070
May1st to 10thNight
40%
540
22%
1620
13%
540
48%
540
30%
1002
May11th to 20thNight
47%
531
18%
1593
11%
531
52%
531
29%
993
May21st to endNight
61%
582
18%
1744
13%
582
64%
582
31%
1086
June1st to 10thNight
62%
540
19%
1603
14%
540
65%
540
33%
962
June11th to 20thNight
75%
540
25%
1440
19%
540
77%
540
49%
800
June21st to endNight
71%
540
23%
1440
16%
540
75%
540
42%
856
July1st to 10thNight
69%
525
16%
1400
13%
525
70%
525
34%
901
July11th to 20thNight
73%
522
20%
1432
16%
522
75%
522
38%
852
July21st to endNight
72%
591
20%
1672
19%
558
74%
558
32%
1028
August1st to 10thNight
74%
537
22%
1705
24%
534
75%
534
33%
1014
August11th to 20thNight
70%
534
18%
1776
19%
534
72%
534
31%
1030
August21st to endNight
73%
594
22%
1980
26%
594
74%
594
31%
1140
September1st to 10thNight
65%
545
25%
1805
26%
545
68%
545
31%
1056
September11th to 20thNight
64%
720
27%
1980
22%
720
67%
720
35%
1226
September21st to endNight
61%
720
30%
1980
21%
720
67%
720
40%
1155
October1st to 10thNight
60%
720
34%
1980
26%
720
65%
720
42%
1091
October11th to 20thNight
45%
720
28%
2016
19%
720
53%
720
31%
1258
October21st to endNight
42%
792
28%
2559
22%
792
52%
792
29%
1528
November1st to 10thNight
51%
740
29%
2406
27%
740
59%
740
33%
1343
November11th to 20thNight
41%
760
30%
2470
20%
760
55%
760
32%
1401
November21st to endNight
40%
760
26%
2470
20%
760
50%
760
27%
1507
December1st to 10thNight
29%
760
19%
2470
12%
760
38%
760
18%
1700
December11th to 20thNight
34%
759
25%
2935
16%
758
45%
758
20%
1805
December21st to endNight
26%
919
12%
4587
10%
907
35%
907
11%
3178

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
12%6%36%6%35%5%6%8%40%
75069
Night
13%6%36%5%3445%7%43%
74699
TransparencyDay
41%6%11%22%16%3
74782
Night
40%5%10%23%18%4
74506
SeeingDay
16%10%23%24%19%8%
14043
Night
17%8%24%30%19%3
23851

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
17%7%46%6%46%35%7%36%
1517
11th to 20thDay
22%10%37%6%345%46%31%
1542
21st to endDay
16%7%36%6%34445%42%
1948
February1st to 10thDay
17%11%5%6%5%3445%7%33%
1800
11th to 20thDay
20%10%38%6%33446%32%
1748
21st to endDay
20%10%5%5%43445%5%36%
1480
March1st to 10thDay
15%9%36%6%35%45%7%39%
1800
11th to 20thDay
19%8%47%7%3435%5%34%
1890
21st to endDay
16%7%47%7%36%5%5%7%33%
2299
April1st to 10thDay
12%5%35%4345%6%8%45%
2160
11th to 20thDay
14%7%36%6%335%46%44%
2134
21st to endDay
13%6%36%6%36%5%5%7%40%
2196
May1st to 10thDay
15%6%35%4345%6%9%41%
2340
11th to 20thDay
13%7%36%5%36%45%7%39%
2301
21st to endDay
8%436%6%47%7%7%10%38%
2531
June1st to 10thDay
8%5%25%5%46%7%7%9%41%
2350
11th to 20thDay
5%3246%46%7%7%11%45%
2520
21st to endDay
4425%6%47%7%9%11%41%
2520
July1st to 10thDay
6%5%37%8%5%8%8%8%11%33%
2520
11th to 20thDay
7%5%36%7%47%7%8%10%36%
2476
21st to endDay
7%5%35%7%5%7%7%8%12%36%
2547
August1st to 10thDay
6%5%27%8%48%7%9%10%35%
2218
11th to 20thDay
9%6%26%7%5%7%6%7%10%35%
2125
21st to endDay
10%6%25%7%47%7%7%9%37%
2376
September1st to 10thDay
10%6%35%6%36%6%7%8%39%
2135
11th to 20thDay
12%6%346%3445%8%45%
1980
21st to endDay
11%5%244245%5%7%51%
1980
October1st to 10thDay
10%5%2442445%7%54%
1980
11th to 20thDay
12%6%34433346%52%
1940
21st to endDay
17%5%26%434445%46%
1796
November1st to 10thDay
12%424323446%57%
1672
11th to 20thDay
14%6%35%32445%7%48%
1710
21st to endDay
14%7%35%5%34446%45%
1710
December1st to 10thDay
22%10%35%5%33446%35%
1710
11th to 20thDay
16%9%35%6%35%5%47%37%
2153
21st to endDay
16%11%47%7%45%5%5%7%28%
2965
January1st to 10thNight
18%8%47%424446%39%
2648
11th to 20thNight
21%10%5%7%6%35%445%30%
2521
21st to endNight
17%8%36%5%34446%40%
2403
February1st to 10thNight
21%10%47%5%245%4433%
2160
11th to 20thNight
22%8%47%5%24345%36%
2098
21st to endNight
24%9%47%5%3344432%
1776
March1st to 10thNight
16%7%36%435%447%40%
2160
11th to 20thNight
17%8%46%6%36%45%6%37%
2070
21st to endNight
14%8%46%5%35%46%7%39%
2070
April1st to 10thNight
10%5%26%5%345%5%7%48%
1800
11th to 20thNight
15%6%2433445%7%48%
1775
21st to endNight
13%6%345%245%6%9%43%
1764
May1st to 10thNight
10%5%36%5%345%5%7%47%
1620
11th to 20thNight
10%6%25%5%35%46%9%45%
1592
21st to endNight
5%427%6%46%6%7%11%42%
1744
June1st to 10thNight
8%6%25%5%345%6%8%47%
1603
11th to 20thNight
3313435%5%8%12%53%
1440
21st to endNight
33145%36%6%8%13%48%
1440
July1st to 10thNight
7%435%5%35%7%8%13%40%
1440
11th to 20thNight
6%5%24436%5%7%13%46%
1480
21st to endNight
6%335%5%47%7%7%11%43%
1771
August1st to 10thNight
6%425%5%446%7%11%46%
1716
11th to 20thNight
5%5%35%5%45%47%11%45%
1776
21st to endNight
8%4145%45%6%7%10%45%
1980
September1st to 10thNight
10%5%36%43445%6%49%
1805
11th to 20thNight
10%425%435%45%7%49%
1980
21st to endNight
10%42442445%7%54%
1980
October1st to 10thNight
10%423323346%61%
1980
11th to 20thNight
15%5%25%5%3335%5%49%
2016
21st to endNight
16%6%24424447%48%
2559
November1st to 10thNight
11%5%35%434345%54%
2406
11th to 20thNight
12%5%35%42345%7%50%
2470
21st to endNight
17%6%35%433346%46%
2470
December1st to 10thNight
20%11%45%4245%45%35%
2470
11th to 20thNight
16%8%36%424445%44%
3042
21st to endNight
17%10%49%7%35%5%5%6%29%
4674

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
48%48%22%14%3
1518
11th to 20thDay
54%5%7%19%14%1
1542
21st to endDay
45%39%25%16%1
1948
February1st to 10thDay
52%48%22%12%2
1800
11th to 20thDay
54%47%20%12%3
1758
21st to endDay
51%39%16%15%6%
1480
March1st to 10thDay
46%48%19%18%5%
1800
11th to 20thDay
51%5%9%19%14%2
1890
21st to endDay
50%6%10%21%12%1
2299
April1st to 10thDay
36%5%11%24%21%3
2160
11th to 20thDay
41%5%6%21%22%5%
2134
21st to endDay
42%5%8%26%16%2
2196
May1st to 10thDay
40%6%12%25%15%2
2340
11th to 20thDay
43%6%12%23%15%1
2305
21st to endDay
37%10%14%24%13%2
2531
June1st to 10thDay
36%9%11%24%18%2
2350
11th to 20thDay
30%8%16%25%18%3
2520
21st to endDay
33%8%16%23%15%5%
2520
July1st to 10thDay
39%11%16%18%12%3
2451
11th to 20thDay
38%9%17%21%12%4
2401
21st to endDay
36%9%17%24%11%2
2405
August1st to 10thDay
39%9%16%24%11%1
2205
11th to 20thDay
42%8%11%21%15%2
2125
21st to endDay
39%9%13%22%14%3
2376
September1st to 10thDay
39%8%11%21%17%3
2135
11th to 20thDay
37%6%10%24%21%2
1980
21st to endDay
32%5%9%27%22%5%
1980
October1st to 10thDay
31%5%8%25%27%5%
1980
11th to 20thDay
34%47%21%26%9%
1940
21st to endDay
41%47%21%24%4
1796
November1st to 10thDay
30%48%25%28%6%
1672
11th to 20thDay
36%37%24%23%6%
1710
21st to endDay
41%37%26%19%5%
1710
December1st to 10thDay
51%37%21%16%2
1710
11th to 20thDay
46%5%9%22%16%1
2150
21st to endDay
52%7%10%21%9%1
2965
January1st to 10thNight
47%49%22%16%2
2648
11th to 20thNight
57%46%18%13%2
2521
21st to endNight
47%48%22%16%3
2403
February1st to 10thNight
54%49%18%14%1
2160
11th to 20thNight
53%26%20%15%4
2099
21st to endNight
55%47%15%14%5%
1776
March1st to 10thNight
44%5%8%15%20%7%
2160
11th to 20thNight
48%5%8%20%16%2
2070
21st to endNight
44%5%10%25%13%2
2070
April1st to 10thNight
35%5%10%25%22%3
1800
11th to 20thNight
37%48%21%22%8%
1775
21st to endNight
38%5%9%27%19%2
1764
May1st to 10thNight
36%6%11%25%19%3
1620
11th to 20thNight
35%8%17%21%17%1
1593
21st to endNight
34%9%15%25%15%2
1745
June1st to 10thNight
32%8%14%25%18%3
1603
11th to 20thNight
22%6%18%33%17%3
1440
21st to endNight
25%9%17%30%15%4
1440
July1st to 10thNight
33%10%19%22%13%4
1400
11th to 20thNight
29%7%19%25%15%5%
1432
21st to endNight
33%9%17%27%13%2
1672
August1st to 10thNight
31%9%14%30%16%1
1705
11th to 20thNight
31%8%19%24%15%2
1776
21st to endNight
32%8%15%26%15%5%
1980
September1st to 10thNight
34%6%11%26%18%4
1805
11th to 20thNight
34%6%10%22%26%3
1980
21st to endNight
29%6%9%24%25%7%
1980
October1st to 10thNight
26%47%24%30%8%
1980
11th to 20thNight
37%5%8%21%23%7%
2016
21st to endNight
37%45%23%25%6%
2559
November1st to 10thNight
33%47%23%26%8%
2406
11th to 20thNight
34%46%22%27%7%
2470
21st to endNight
40%47%25%20%5%
2470
December1st to 10thNight
50%5%8%19%15%3
2470
11th to 20thNight
42%46%23%21%3
3044
21st to endNight
55%5%8%19%12%2
4674

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
24%19%36%14%7%1
270
11th to 20thDay
32%22%26%14%5%2
255
21st to endDay
20%22%41%13%4
264
February1st to 10thDay
27%19%33%17%31
240
11th to 20thDay
41%18%29%11%2
240
21st to endDay
36%16%35%11%2
198
March1st to 10thDay
24%20%36%16%4
240
11th to 20thDay
25%22%32%14%7%1
330
21st to endDay
23%19%31%17%8%1
462
April1st to 10thDay
18%19%27%27%9%2
420
11th to 20thDay
21%12%30%25%10%2
412
21st to endDay
18%15%32%19%13%3
420
May1st to 10thDay
20%12%26%25%12%4
423
11th to 20thDay
16%6%27%26%16%9%
447
21st to endDay
11%419%29%23%14%
485
June1st to 10thDay
10%5%19%23%25%17%
460
11th to 20thDay
6%418%28%30%13%
630
21st to endDay
7%321%35%20%13%
630
July1st to 10thDay
10%114%29%28%18%
621
11th to 20thDay
9%311%28%33%16%
574
21st to endDay
8%312%28%29%21%
488
August1st to 10thDay
11%211%27%33%15%
446
11th to 20thDay
13%410%33%32%8%
439
21st to endDay
13%211%23%34%17%
495
September1st to 10thDay
11%212%28%33%14%
450
11th to 20thDay
15%210%25%31%17%
450
21st to endDay
16%5%16%27%28%9%
450
October1st to 10thDay
14%420%28%26%8%
450
11th to 20thDay
15%14%29%26%12%4
410
21st to endDay
27%12%25%27%7%2
297
November1st to 10thDay
17%11%29%27%13%3
270
11th to 20thDay
15%16%39%24%6%
270
21st to endDay
20%14%34%19%10%3
270
December1st to 10thDay
28%17%31%16%7%
270
11th to 20thDay
20%19%32%18%10%1
270
21st to endDay
26%20%33%18%4
297
January1st to 10thNight
22%16%30%27%5%
950
11th to 20thNight
27%15%30%23%5%
856
21st to endNight
21%13%36%28%3
792
February1st to 10thNight
24%13%33%25%4
720
11th to 20thNight
28%15%31%23%2
703
21st to endNight
30%16%31%21%2
592
March1st to 10thNight
21%14%31%27%7%
720
11th to 20thNight
21%11%33%28%7%1
720
21st to endNight
19%13%31%28%9%
684
April1st to 10thNight
14%10%34%33%9%1
540
11th to 20thNight
17%12%33%27%10%1
533
21st to endNight
16%10%31%31%11%1
540
May1st to 10thNight
13%7%33%29%17%1
540
11th to 20thNight
13%429%30%21%3
531
21st to endNight
7%219%36%32%5%
584
June1st to 10thNight
11%215%36%31%4
540
11th to 20thNight
5%113%41%34%6%
540
21st to endNight
5%115%37%34%7%
540
July1st to 10thNight
9%110%31%37%13%
525
11th to 20thNight
9%110%28%43%10%
522
21st to endNight
7%29%32%43%8%
591
August1st to 10thNight
7%17%32%47%6%
537
11th to 20thNight
7%29%37%37%7%
534
21st to endNight
9%27%31%43%8%
594
September1st to 10thNight
12%210%29%42%5%
545
11th to 20thNight
12%213%31%37%6%
720
21st to endNight
12%218%31%34%4
720
October1st to 10thNight
11%5%17%30%30%6%
720
11th to 20thNight
18%7%23%32%18%1
720
21st to endNight
18%6%28%29%17%2
792
November1st to 10thNight
14%7%21%36%19%3
740
11th to 20thNight
14%10%32%31%13%
760
21st to endNight
19%10%26%32%12%1
760
December1st to 10thNight
28%10%27%28%7%1
760
11th to 20thNight
22%9%30%31%8%1
760
21st to endNight
27%12%29%27%5%
926
Page generated at 2024-01-13 00:38:13. Version ac07

Copyright 2024 Attilla Danko


Nashville Clear Sky Chart |Charts Home