Louisville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Louisville clear sky chart from 2005-11-06 to 2024-01-15.

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
43%
24079
19%
74493
14%
24023
49%
24023
24%
49050

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
24%
950
14%
2648
6%
946
32%
946
17%
1935
January11th to 20thNight
21%
897
14%
2557
7%
897
28%
897
15%
1951
January21st to endNight
23%
792
16%
2545
8%
792
32%
792
17%
1786
February1st to 10thNight
22%
720
12%
2160
5%
720
29%
720
14%
1635
February11th to 20thNight
20%
703
17%
2099
7%
700
30%
700
18%
1484
February21st to endNight
16%
592
14%
1776
6%
592
24%
592
14%
1307
March1st to 10thNight
26%
720
18%
2160
10%
720
34%
720
22%
1442
March11th to 20thNight
26%
720
16%
2026
7%
720
33%
720
21%
1436
March21st to endNight
33%
755
14%
2141
8%
755
37%
755
19%
1531
April1st to 10thNight
35%
540
22%
1800
13%
540
48%
540
24%
1105
April11th to 20thNight
38%
533
22%
1775
17%
533
47%
533
24%
1118
April21st to endNight
35%
540
19%
1656
11%
540
44%
540
23%
1113
May1st to 10thNight
36%
540
15%
1620
8%
540
42%
540
23%
1106
May11th to 20thNight
52%
531
17%
1593
12%
531
55%
531
23%
1066
May21st to endNight
60%
582
18%
1745
13%
582
64%
582
28%
1124
June1st to 10thNight
63%
540
20%
1544
16%
540
66%
540
36%
921
June11th to 20thNight
67%
540
23%
1440
17%
540
69%
540
39%
853
June21st to endNight
69%
540
22%
1440
17%
540
73%
540
41%
846
July1st to 10thNight
64%
525
17%
1400
13%
525
64%
525
31%
910
July11th to 20thNight
75%
522
22%
1397
19%
522
76%
522
41%
822
July21st to endNight
69%
591
22%
1672
20%
558
72%
558
33%
1014
August1st to 10thNight
75%
537
23%
1600
22%
534
76%
534
37%
927
August11th to 20thNight
71%
534
22%
1712
22%
534
73%
534
31%
1016
August21st to endNight
76%
594
25%
1980
27%
594
78%
594
40%
1021
September1st to 10thNight
68%
580
23%
1840
23%
580
71%
580
33%
1076
September11th to 20thNight
64%
720
30%
1980
23%
720
67%
720
39%
1180
September21st to endNight
57%
720
29%
1980
22%
720
62%
720
37%
1180
October1st to 10thNight
60%
720
30%
1980
24%
720
65%
720
41%
1131
October11th to 20thNight
45%
720
27%
2056
18%
720
53%
720
29%
1291
October21st to endNight
36%
792
23%
2574
17%
792
48%
792
25%
1621
November1st to 10thNight
44%
740
26%
2406
21%
740
54%
740
29%
1402
November11th to 20thNight
34%
760
26%
2470
17%
760
46%
760
25%
1535
November21st to endNight
37%
760
21%
2470
16%
760
45%
760
21%
1632
December1st to 10thNight
28%
760
15%
2470
8%
760
37%
760
18%
1726
December11th to 20thNight
28%
759
17%
2976
12%
759
37%
759
15%
2045
December21st to endNight
20%
1010
9%
4805
7%
997
28%
997
9%
3762

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
14%7%36%5%35%5%6%8%39%
75009
Night
15%7%36%5%3445%7%41%
74778
TransparencyDay
43%7%11%22%15%2
74722
Night
43%6%11%22%16%3
74585
SeeingDay
17%10%25%24%17%8%
14214
Night
18%8%26%30%17%2
24088

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%10%49%5%3345%6%33%
1517
11th to 20thDay
20%12%5%9%6%3435%6%28%
1493
21st to endDay
15%11%5%8%6%35%45%7%32%
1809
February1st to 10thDay
18%11%5%9%5%34347%31%
1800
11th to 20thDay
18%8%46%6%45%5%5%6%34%
1748
21st to endDay
18%11%48%6%35%5%46%30%
1480
March1st to 10thDay
18%7%36%5%35%447%38%
1800
11th to 20thDay
19%9%46%6%35%35%8%32%
1934
21st to endDay
17%10%47%6%45%5%5%7%30%
2231
April1st to 10thDay
13%6%35%6%45%5%7%7%41%
2160
11th to 20thDay
17%7%36%5%345%5%6%39%
2134
21st to endDay
17%7%35%6%345%6%7%37%
2304
May1st to 10thDay
18%6%35%6%35%5%6%7%35%
2340
11th to 20thDay
16%8%36%5%45%5%5%6%36%
2301
21st to endDay
8%5%26%8%47%7%8%10%36%
2531
June1st to 10thDay
11%425%5%35%5%6%8%45%
2412
11th to 20thDay
7%4245%45%6%7%10%46%
2520
21st to endDay
7%425%5%35%6%7%11%43%
2520
July1st to 10thDay
12%6%25%6%46%7%7%10%36%
2520
11th to 20thDay
8%5%245%45%6%7%10%43%
2512
21st to endDay
9%435%5%35%6%7%10%42%
2547
August1st to 10thDay
8%5%25%5%36%6%8%10%42%
2327
11th to 20thDay
8%5%36%6%45%6%7%9%41%
2186
21st to endDay
7%6%25%5%36%5%5%9%47%
2376
September1st to 10thDay
14%5%26%4245%6%6%46%
2102
11th to 20thDay
10%5%25%435%5%7%7%48%
1980
21st to endDay
12%5%25%5%2445%6%51%
1980
October1st to 10thDay
11%4245%33446%54%
1980
11th to 20thDay
13%5%35%5%335%5%8%46%
1897
21st to endDay
17%8%25%5%3445%6%41%
1782
November1st to 10thDay
11%6%15%41345%6%54%
1672
11th to 20thDay
16%9%45%42345%6%42%
1710
21st to endDay
18%9%36%33435%6%40%
1710
December1st to 10thDay
21%11%46%6%23345%33%
1710
11th to 20thDay
14%12%6%9%6%44446%32%
2153
21st to endDay
21%16%47%5%36%5%46%23%
2831
January1st to 10thNight
16%11%49%6%345%5%5%32%
2648
11th to 20thNight
21%11%5%8%6%35%445%29%
2557
21st to endNight
17%10%48%5%3445%6%34%
2545
February1st to 10thNight
23%10%5%7%6%3445%5%28%
2160
11th to 20thNight
18%8%47%6%34435%36%
2098
21st to endNight
23%11%37%5%34446%30%
1776
March1st to 10thNight
18%8%35%5%34445%42%
2160
11th to 20thNight
20%9%46%5%33446%36%
2026
21st to endNight
19%9%46%5%3445%6%34%
2141
April1st to 10thNight
12%6%35%5%35%5%49%44%
1800
11th to 20thNight
15%8%35%5%2435%7%42%
1775
21st to endNight
16%6%46%5%45%45%6%40%
1656
May1st to 10thNight
16%6%36%6%345%6%7%38%
1620
11th to 20thNight
13%6%26%5%36%5%6%8%40%
1592
21st to endNight
7%425%6%37%7%7%10%41%
1744
June1st to 10thNight
10%4235%35%5%5%10%49%
1544
11th to 20thNight
7%335%43446%10%51%
1440
21st to endNight
5%2235%35%7%6%12%50%
1440
July1st to 10thNight
9%5%26%5%345%6%9%45%
1440
11th to 20thNight
6%424445%46%11%51%
1445
21st to endNight
8%325%5%35%5%6%9%48%
1771
August1st to 10thNight
7%424335%6%6%10%50%
1611
11th to 20thNight
6%4246%46%7%7%10%45%
1712
21st to endNight
6%42432346%10%55%
1980
September1st to 10thNight
12%4245%24448%50%
1840
11th to 20thNight
10%425%42445%8%52%
1980
21st to endNight
11%425%433447%53%
1980
October1st to 10thNight
9%424323437%57%
1980
11th to 20thNight
14%5%25%5%24446%48%
2056
21st to endNight
18%7%25%434445%45%
2574
November1st to 10thNight
12%6%25%434345%52%
2406
11th to 20thNight
14%7%35%434447%45%
2470
21st to endNight
18%9%445%34346%41%
2470
December1st to 10thNight
21%10%45%434445%35%
2470
11th to 20thNight
19%10%46%5%35%445%35%
3042
21st to endNight
20%16%5%8%7%45%5%35%22%
4829

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
52%5%9%21%11%2
1518
11th to 20thDay
59%49%18%9%1
1493
21st to endDay
52%411%24%7%1
1809
February1st to 10thDay
55%49%22%9%2
1800
11th to 20thDay
51%5%10%22%10%2
1758
21st to endDay
55%5%10%18%10%3
1480
March1st to 10thDay
47%49%23%15%1
1800
11th to 20thDay
52%5%10%19%11%2
1934
21st to endDay
53%6%11%20%9%2
2231
April1st to 10thDay
41%7%11%24%16%1
2160
11th to 20thDay
46%5%8%21%17%3
2134
21st to endDay
46%6%10%24%12%3
2304
May1st to 10thDay
47%8%12%21%11%1
2340
11th to 20thDay
49%7%11%18%14%1
2305
21st to endDay
40%12%15%18%13%1
2531
June1st to 10thDay
36%6%11%26%17%3
2412
11th to 20thDay
32%10%13%25%18%2
2520
21st to endDay
33%10%14%21%18%4
2520
July1st to 10thDay
41%9%13%20%14%3
2451
11th to 20thDay
34%9%15%23%15%4
2437
21st to endDay
35%9%15%24%14%2
2405
August1st to 10thDay
34%10%15%24%16%2
2314
11th to 20thDay
37%8%13%25%15%2
2186
21st to endDay
32%8%13%24%17%6%
2376
September1st to 10thDay
38%6%11%23%17%5%
2102
11th to 20thDay
33%7%11%23%21%3
1980
21st to endDay
34%5%9%24%25%3
1980
October1st to 10thDay
32%5%9%25%25%4
1980
11th to 20thDay
37%5%7%25%22%4
1897
21st to endDay
43%5%9%25%14%3
1782
November1st to 10thDay
33%410%28%20%5%
1672
11th to 20thDay
43%47%23%18%5%
1710
21st to endDay
46%38%24%17%1
1710
December1st to 10thDay
55%311%20%10%1
1710
11th to 20thDay
55%48%20%12%1
2150
21st to endDay
61%5%11%15%7%
2831
January1st to 10thNight
53%5%9%18%13%2
2648
11th to 20thNight
58%5%10%17%9%1
2557
21st to endNight
52%5%10%22%9%2
2545
February1st to 10thNight
58%5%11%18%6%1
2160
11th to 20thNight
52%48%21%13%1
2099
21st to endNight
57%5%11%14%11%3
1776
March1st to 10thNight
46%5%8%22%17%3
2160
11th to 20thNight
49%5%11%20%12%2
2026
21st to endNight
50%6%12%22%8%2
2141
April1st to 10thNight
39%6%11%24%17%3
1800
11th to 20thNight
43%410%19%19%6%
1775
21st to endNight
45%6%9%23%13%3
1656
May1st to 10thNight
45%7%11%23%11%3
1620
11th to 20thNight
42%9%13%20%15%2
1593
21st to endNight
35%11%14%21%16%3
1745
June1st to 10thNight
31%7%11%27%20%4
1544
11th to 20thNight
28%8%15%24%21%5%
1440
21st to endNight
26%8%18%23%18%7%
1440
July1st to 10thNight
35%9%12%23%16%4
1400
11th to 20thNight
28%7%15%26%19%5%
1397
21st to endNight
32%9%13%29%16%2
1672
August1st to 10thNight
28%8%17%27%17%3
1600
11th to 20thNight
30%11%14%26%17%2
1712
21st to endNight
24%6%18%27%20%5%
1980
September1st to 10thNight
33%6%12%23%20%6%
1840
11th to 20thNight
31%6%10%26%23%5%
1980
21st to endNight
32%5%7%25%26%5%
1980
October1st to 10thNight
28%5%11%24%27%5%
1980
11th to 20thNight
37%6%7%23%23%4
2056
21st to endNight
42%48%22%20%4
2574
November1st to 10thNight
37%39%23%23%5%
2406
11th to 20thNight
41%47%21%21%5%
2470
21st to endNight
47%49%22%17%1
2470
December1st to 10thNight
51%5%11%20%12%1
2470
11th to 20thNight
51%5%9%20%13%2
3044
21st to endNight
65%5%10%13%7%1
4829

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
25%17%33%19%6%
270
11th to 20thDay
28%21%32%15%4
252
21st to endDay
22%25%36%15%3
264
February1st to 10thDay
25%19%42%11%3
240
11th to 20thDay
31%22%37%9%2
240
21st to endDay
31%14%40%12%3
198
March1st to 10thDay
21%22%38%17%2
240
11th to 20thDay
24%14%40%15%6%1
374
21st to endDay
26%17%31%19%7%1
462
April1st to 10thDay
17%16%30%24%11%1
420
11th to 20thDay
23%15%23%24%11%3
412
21st to endDay
20%15%33%20%9%2
420
May1st to 10thDay
21%15%30%23%7%5%
423
11th to 20thDay
20%9%25%27%14%5%
447
21st to endDay
12%5%23%26%21%13%
485
June1st to 10thDay
11%7%21%28%22%11%
522
11th to 20thDay
5%6%19%35%23%11%
630
21st to endDay
10%5%23%30%22%11%
630
July1st to 10thDay
14%215%23%24%22%
621
11th to 20thDay
8%416%32%26%14%
610
21st to endDay
11%214%29%30%15%
488
August1st to 10thDay
12%312%28%28%17%
446
11th to 20thDay
13%316%29%26%13%
439
21st to endDay
10%311%26%33%17%
495
September1st to 10thDay
11%315%26%34%10%
450
11th to 20thDay
10%315%25%34%13%
450
21st to endDay
14%7%18%25%25%11%
450
October1st to 10thDay
11%421%36%21%7%
450
11th to 20thDay
14%14%31%26%11%3
442
21st to endDay
25%15%29%23%7%
297
November1st to 10thDay
14%10%33%28%12%4
270
11th to 20thDay
22%16%30%24%6%2
270
21st to endDay
23%11%35%23%8%
270
December1st to 10thDay
23%22%27%20%7%1
270
11th to 20thDay
22%16%36%19%6%1
270
21st to endDay
30%20%31%15%3
297
January1st to 10thNight
21%17%31%27%4
950
11th to 20thNight
26%14%33%22%4
897
21st to endNight
21%15%38%25%2
792
February1st to 10thNight
29%10%33%25%3
720
11th to 20thNight
23%15%38%23%1
703
21st to endNight
28%13%39%19%2
592
March1st to 10thNight
23%13%34%26%4
720
11th to 20thNight
24%10%35%23%7%
720
21st to endNight
23%12%27%30%7%
755
April1st to 10thNight
16%9%35%30%10%
540
11th to 20thNight
19%9%29%30%13%1
533
21st to endNight
19%6%35%31%8%1
540
May1st to 10thNight
17%7%33%27%15%1
540
11th to 20thNight
16%6%17%39%18%4
531
21st to endNight
8%218%38%27%6%
584
June1st to 10thNight
11%218%39%27%3
540
11th to 20thNight
7%416%41%30%3
540
21st to endNight
5%117%42%31%4
540
July1st to 10thNight
12%210%29%39%10%
525
11th to 20thNight
6%39%34%41%7%
522
21st to endNight
9%211%37%35%6%
591
August1st to 10thNight
9%18%34%43%5%
537
11th to 20thNight
6%111%39%36%7%
534
21st to endNight
7%18%34%45%5%
594
September1st to 10thNight
13%110%34%37%5%
580
11th to 20thNight
10%415%29%37%5%
720
21st to endNight
12%5%21%30%29%3
720
October1st to 10thNight
11%419%35%26%5%
720
11th to 20thNight
16%7%26%33%16%2
720
21st to endNight
22%7%31%28%12%
792
November1st to 10thNight
14%8%27%33%16%1
740
11th to 20thNight
17%11%33%28%11%
760
21st to endNight
23%10%25%31%11%
760
December1st to 10thNight
26%10%32%27%5%
760
11th to 20thNight
24%9%34%26%7%1
760
21st to endNight
29%14%31%22%4
1016
Page generated at 2024-01-12 07:31:46. Version ac07

Copyright 2024 Attilla Danko


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