Martz-Kohl Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Martz-Kohl Observatory clear sky chart from 2005-11-06 to 2024-01-31.

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
27%
23130
11%
75090
8%
23078
32%
23078
13%
57126

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
7%
757
6%
2629
3%
757
12%
757
4%
2291
January11th to 20thNight
11%
760
4%
2470
3%
760
13%
760
5%
2137
January21st to endNight
11%
835
5%
2711
3%
835
15%
835
5%
2378
February1st to 10thNight
9%
720
5%
2340
2%
720
14%
720
6%
1997
February11th to 20thNight
7%
702
6%
2275
2%
700
13%
700
5%
1949
February21st to endNight
11%
592
9%
1827
2%
592
20%
592
8%
1502
March1st to 10thNight
14%
720
11%
1980
6%
720
19%
720
10%
1610
March11th to 20thNight
20%
720
14%
1980
7%
720
26%
720
13%
1533
March21st to endNight
19%
792
14%
2178
6%
792
26%
792
13%
1705
April1st to 10thNight
21%
720
11%
1831
3%
720
26%
720
16%
1422
April11th to 20thNight
24%
711
13%
1775
5%
711
28%
711
20%
1310
April21st to endNight
30%
553
15%
1633
6%
553
36%
553
18%
1170
May1st to 10thNight
34%
540
13%
1620
8%
540
37%
540
17%
1167
May11th to 20thNight
36%
419
15%
1481
11%
419
43%
419
16%
1010
May21st to endNight
44%
388
17%
1551
18%
388
50%
388
21%
930
June1st to 10thNight
41%
360
13%
1440
12%
360
50%
360
19%
918
June11th to 20thNight
41%
360
14%
1440
15%
360
49%
360
18%
899
June21st to endNight
42%
360
15%
1440
16%
360
50%
360
21%
881
July1st to 10thNight
57%
350
14%
1400
19%
350
60%
350
24%
834
July11th to 20thNight
55%
392
17%
1436
20%
392
58%
392
26%
839
July21st to endNight
54%
591
14%
1672
11%
558
57%
558
27%
1073
August1st to 10thNight
60%
537
17%
1600
14%
534
62%
534
30%
1002
August11th to 20thNight
55%
534
15%
1598
11%
534
57%
534
25%
1071
August21st to endNight
54%
715
18%
1903
11%
715
55%
715
29%
1253
September1st to 10thNight
46%
720
17%
1800
10%
720
48%
720
29%
1238
September11th to 20thNight
51%
720
23%
1888
16%
720
54%
720
32%
1207
September21st to endNight
41%
720
17%
2027
14%
720
43%
720
20%
1460
October1st to 10thNight
39%
720
16%
2160
14%
720
43%
720
21%
1500
October11th to 20thNight
25%
720
11%
2160
7%
720
32%
720
15%
1601
October21st to endNight
18%
792
14%
2376
8%
792
26%
792
12%
1870
November1st to 10thNight
28%
740
16%
2356
12%
740
34%
740
17%
1671
November11th to 20thNight
18%
760
11%
2660
7%
760
25%
760
10%
2074
November21st to endNight
15%
760
8%
2660
5%
760
20%
760
8%
2166
December1st to 10thNight
9%
760
4%
2660
3%
760
11%
760
3%
2360
December11th to 20thNight
11%
760
3%
3274
1%
759
13%
759
4%
2798
December21st to endNight
8%
830
3%
4859
1%
817
12%
817
2%
4300

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
18%12%5%8%6%3445%6%28%
74814
Night
18%14%5%8%6%34445%27%
75312
TransparencyDay
56%7%11%16%9%1
74531
Night
59%6%11%15%8%1
75129
SeeingDay
26%18%28%17%9%3
13521
Night
25%16%26%22%10%1
23141

By Month

Percentage Cloud Cover NE (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
15%20%11%14%9%35%44314%
1536
11th to 20thDay
17%21%8%15%10%3433412%
1710
21st to endDay
14%17%11%17%10%5%444410%
1872
February1st to 10thDay
19%18%9%14%10%4432314%
1620
11th to 20thDay
15%16%8%16%11%3433416%
1573
21st to endDay
19%17%5%12%9%2444420%
1427
March1st to 10thDay
17%14%7%12%6%34435%24%
1977
11th to 20thDay
16%17%8%8%6%33346%26%
1980
21st to endDay
21%14%6%8%5%23345%28%
2178
April1st to 10thDay
16%16%6%7%5%34446%29%
2128
11th to 20thDay
21%13%345%345%46%32%
2137
21st to endDay
22%11%36%5%34445%33%
2340
May1st to 10thDay
21%11%37%6%345%46%29%
2340
11th to 20thDay
20%10%47%5%345%5%5%32%
2410
21st to endDay
15%5%35%5%35%6%6%8%39%
2725
June1st to 10thDay
19%7%36%6%345%6%7%35%
2520
11th to 20thDay
17%6%35%6%36%6%6%9%34%
2520
21st to endDay
18%6%25%5%45%5%5%9%36%
2520
July1st to 10thDay
12%5%25%6%45%5%6%8%40%
2520
11th to 20thDay
14%6%35%7%46%6%7%9%33%
2473
21st to endDay
13%7%36%6%46%6%7%9%33%
2547
August1st to 10thDay
13%7%26%6%45%6%7%9%35%
2327
11th to 20thDay
15%6%37%7%46%6%7%9%29%
2303
21st to endDay
17%6%35%6%45%5%6%9%34%
2434
September1st to 10thDay
21%6%36%5%345%5%7%36%
2160
11th to 20thDay
16%6%35%6%345%5%8%39%
2070
21st to endDay
20%8%46%6%35%5%5%7%31%
1932
October1st to 10thDay
22%8%36%6%345%5%7%31%
1800
11th to 20thDay
24%12%37%7%34446%27%
1800
21st to endDay
27%15%5%7%5%34445%22%
1980
November1st to 10thDay
15%17%46%6%3435%6%31%
1717
11th to 20thDay
18%20%6%8%424447%21%
1520
21st to endDay
20%24%6%8%5%3445%5%17%
1520
December1st to 10thDay
19%25%13%12%5%2334311%
1520
11th to 20thDay
17%21%9%15%5%33445%14%
1906
21st to endDay
25%25%10%9%5%3333311%
2772
January1st to 10thNight
18%20%9%15%9%35%33412%
2629
11th to 20thNight
18%19%10%14%9%3433413%
2470
21st to endNight
15%19%10%14%10%5%5%43312%
2711
February1st to 10thNight
18%18%7%13%11%4433315%
2340
11th to 20thNight
15%15%8%16%11%45%44315%
2273
21st to endNight
18%15%7%15%8%3433321%
1827
March1st to 10thNight
15%14%8%12%7%445%4422%
1970
11th to 20thNight
18%14%7%9%6%34335%28%
1979
21st to endNight
17%16%7%7%6%3434427%
2178
April1st to 10thNight
19%13%6%6%5%345%46%29%
1831
11th to 20thNight
20%12%345%34446%35%
1775
21st to endNight
17%12%35%5%35%45%7%32%
1633
May1st to 10thNight
20%9%26%6%345%5%7%33%
1620
11th to 20thNight
15%8%37%6%36%5%5%7%36%
1480
21st to endNight
14%6%24435%5%5%9%45%
1550
June1st to 10thNight
14%8%36%6%35%5%6%8%37%
1440
11th to 20thNight
15%7%35%5%35%5%5%8%39%
1440
21st to endNight
15%6%16%4245%6%8%42%
1440
July1st to 10thNight
9%6%25%6%3446%8%47%
1440
11th to 20thNight
13%425%5%345%6%8%45%
1484
21st to endNight
13%5%25%6%35%5%7%8%41%
1771
August1st to 10thNight
10%6%245%35%5%7%9%44%
1611
11th to 20thNight
13%6%35%6%446%7%9%39%
1598
21st to endNight
13%5%245%35%46%9%43%
1903
September1st to 10thNight
17%6%3443445%6%42%
1800
11th to 20thNight
14%7%24423447%48%
1888
21st to endNight
20%7%36%5%35%5%5%6%34%
2027
October1st to 10thNight
20%7%25%5%3445%6%38%
2160
11th to 20thNight
23%11%35%6%35%45%7%29%
2160
21st to endNight
30%13%35%5%3434426%
2376
November1st to 10thNight
16%15%46%5%33436%35%
2356
11th to 20thNight
18%19%5%7%6%35%5%5%5%22%
2660
21st to endNight
18%22%7%8%5%34445%20%
2660
December1st to 10thNight
22%23%12%10%5%3343311%
2660
11th to 20thNight
19%22%9%15%6%3333314%
3288
21st to endNight
24%23%8%11%7%343449%
4884

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
75%5%9%8%3
1537
11th to 20thDay
77%48%8%3
1710
21st to endDay
79%47%6%31
1872
February1st to 10thDay
78%48%7%3
1620
11th to 20thDay
73%46%11%5%
1582
21st to endDay
67%5%10%12%42
1427
March1st to 10thDay
63%5%11%15%6%
1980
11th to 20thDay
60%5%9%15%8%2
1980
21st to endDay
59%5%7%17%10%2
2178
April1st to 10thDay
56%5%12%16%11%1
2128
11th to 20thDay
52%7%9%19%11%2
2137
21st to endDay
54%5%10%17%12%2
2340
May1st to 10thDay
56%6%10%17%9%2
2340
11th to 20thDay
53%6%10%18%11%1
2414
21st to endDay
42%9%16%20%12%1
2725
June1st to 10thDay
47%7%12%19%13%1
2520
11th to 20thDay
46%8%14%20%11%
2520
21st to endDay
44%7%13%22%12%
2520
July1st to 10thDay
41%9%12%23%14%1
2450
11th to 20thDay
44%9%16%19%12%
2398
21st to endDay
44%10%14%19%12%1
2405
August1st to 10thDay
41%10%16%23%10%
2314
11th to 20thDay
48%11%15%19%7%1
2303
21st to endDay
45%9%13%22%10%2
2434
September1st to 10thDay
47%7%11%21%13%1
2160
11th to 20thDay
43%7%12%24%13%1
2070
21st to endDay
52%7%10%21%9%1
1932
October1st to 10thDay
52%8%12%15%12%2
1800
11th to 20thDay
58%7%13%15%7%1
1800
21st to endDay
66%5%9%13%6%1
1980
November1st to 10thDay
55%6%11%15%11%2
1717
11th to 20thDay
63%6%10%13%6%2
1520
21st to endDay
71%5%10%10%41
1520
December1st to 10thDay
79%48%8%2
1520
11th to 20thDay
73%6%11%8%2
1906
21st to endDay
78%6%8%6%1
2772
January1st to 10thNight
78%5%7%7%4
2629
11th to 20thNight
76%49%7%31
2470
21st to endNight
77%5%7%7%31
2711
February1st to 10thNight
75%410%9%3
2340
11th to 20thNight
75%47%9%4
2275
21st to endNight
70%48%12%7%1
1827
March1st to 10thNight
65%6%8%17%5%
1980
11th to 20thNight
60%5%10%16%9%1
1980
21st to endNight
61%5%6%14%12%2
2178
April1st to 10thNight
56%6%11%16%9%
1831
11th to 20thNight
51%6%11%18%12%2
1775
21st to endNight
50%7%11%18%10%3
1633
May1st to 10thNight
50%8%10%19%10%2
1620
11th to 20thNight
49%7%10%20%12%2
1481
21st to endNight
37%10%13%26%12%3
1551
June1st to 10thNight
44%7%13%22%13%
1440
11th to 20thNight
41%9%13%22%14%2
1440
21st to endNight
39%9%12%27%12%1
1440
July1st to 10thNight
36%9%13%23%18%2
1400
11th to 20thNight
35%8%14%26%16%2
1436
21st to endNight
38%9%16%20%16%1
1672
August1st to 10thNight
35%9%16%30%10%1
1600
11th to 20thNight
40%10%17%25%9%
1598
21st to endNight
37%9%16%24%12%2
1903
September1st to 10thNight
41%7%14%24%12%2
1800
11th to 20thNight
37%5%15%24%17%1
1888
21st to endNight
49%7%13%18%12%1
2027
October1st to 10thNight
47%7%12%19%15%1
2160
11th to 20thNight
54%7%12%16%9%1
2160
21st to endNight
62%6%10%14%7%1
2376
November1st to 10thNight
51%7%11%19%10%3
2356
11th to 20thNight
62%7%10%13%6%3
2660
21st to endNight
68%5%11%12%3
2660
December1st to 10thNight
79%5%7%7%2
2660
11th to 20thNight
76%5%10%7%2
3288
21st to endNight
80%5%8%6%1
4884

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
33%30%24%10%3
189
11th to 20thDay
34%32%24%7%2
270
21st to endDay
31%30%28%9%1
294
February1st to 10thDay
40%28%28%3
240
11th to 20thDay
37%35%24%4
240
21st to endDay
43%23%28%6%1
254
March1st to 10thDay
34%25%28%10%3
420
11th to 20thDay
32%24%30%10%31
420
21st to endDay
36%21%24%13%41
462
April1st to 10thDay
32%23%26%14%41
420
11th to 20thDay
32%22%22%13%9%3
412
21st to endDay
29%18%32%15%41
420
May1st to 10thDay
31%22%23%15%8%2
423
11th to 20thDay
26%17%27%20%8%2
447
21st to endDay
16%14%29%22%13%5%
485
June1st to 10thDay
20%15%32%21%9%2
450
11th to 20thDay
20%14%28%22%13%2
450
21st to endDay
20%13%34%22%9%2
450
July1st to 10thDay
13%9%27%24%19%7%
445
11th to 20thDay
14%11%26%28%15%5%
444
21st to endDay
14%10%35%25%12%5%
488
August1st to 10thDay
11%10%27%27%16%9%
446
11th to 20thDay
18%8%27%24%14%9%
439
21st to endDay
17%10%27%24%13%8%
495
September1st to 10thDay
20%11%24%22%16%7%
450
11th to 20thDay
14%6%27%23%21%8%
450
21st to endDay
20%18%26%18%14%4
450
October1st to 10thDay
24%12%28%18%14%5%
450
11th to 20thDay
31%20%28%14%6%1
450
21st to endDay
38%18%27%14%2
495
November1st to 10thDay
29%20%26%18%5%3
355
11th to 20thDay
39%22%24%9%41
180
21st to endDay
37%21%37%5%1
180
December1st to 10thDay
38%29%25%431
180
11th to 20thDay
38%27%26%8%1
180
21st to endDay
42%22%31%5%
198
January1st to 10thNight
30%27%29%10%3
760
11th to 20thNight
32%26%27%13%2
760
21st to endNight
28%26%29%15%2
835
February1st to 10thNight
34%23%30%13%1
720
11th to 20thNight
29%26%33%10%2
703
21st to endNight
31%26%29%12%2
592
March1st to 10thNight
27%23%31%16%3
720
11th to 20thNight
32%21%24%19%5%
720
21st to endNight
27%19%30%18%41
792
April1st to 10thNight
28%19%29%21%4
720
11th to 20thNight
28%16%29%19%7%1
711
21st to endNight
23%12%30%29%6%
553
May1st to 10thNight
23%11%24%30%12%1
540
11th to 20thNight
18%11%30%34%8%
419
21st to endNight
15%7%28%29%18%2
389
June1st to 10thNight
16%430%35%14%1
360
11th to 20thNight
17%10%25%35%12%
360
21st to endNight
15%5%31%33%15%
360
July1st to 10thNight
11%6%19%41%20%4
350
11th to 20thNight
12%5%20%37%25%2
392
21st to endNight
15%5%18%38%23%1
591
August1st to 10thNight
11%417%36%29%2
537
11th to 20thNight
15%5%17%30%32%2
534
21st to endNight
14%5%20%33%24%4
715
September1st to 10thNight
20%6%21%29%21%3
720
11th to 20thNight
16%7%20%28%25%4
720
21st to endNight
22%12%19%26%17%4
720
October1st to 10thNight
22%10%24%24%16%2
720
11th to 20thNight
29%15%27%22%6%1
720
21st to endNight
38%12%29%18%3
792
November1st to 10thNight
26%16%27%24%7%
740
11th to 20thNight
32%20%26%16%5%1
760
21st to endNight
31%23%27%14%4
760
December1st to 10thNight
37%25%24%11%3
760
11th to 20thNight
32%27%25%13%3
760
21st to endNight
32%24%30%12%1
836
Page generated at 2024-01-28 05:26:36. Version ac07

Copyright 2024 Attilla Danko


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