Colter/Menke Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Colter/Menke Observatory clear sky chart from 2005-11-06 to 2024-01-11.

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
35%
24407
21%
74679
12%
24345
44%
24345
25%
47663

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
18%
950
18%
2648
6%
946
29%
946
19%
1824
January11th to 20thNight
18%
905
20%
2353
6%
905
28%
905
19%
1689
January21st to endNight
17%
990
19%
2574
5%
990
28%
990
19%
1836
February1st to 10thNight
16%
900
15%
2340
3%
900
24%
900
17%
1709
February11th to 20thNight
16%
769
18%
2165
5%
766
26%
766
18%
1473
February21st to endNight
14%
592
19%
1776
5%
592
26%
592
18%
1218
March1st to 10thNight
17%
649
19%
2089
6%
649
29%
649
20%
1345
March11th to 20thNight
22%
540
18%
1980
10%
540
34%
540
16%
1325
March21st to endNight
16%
594
11%
2102
5%
594
25%
594
12%
1515
April1st to 10thNight
25%
540
21%
1800
10%
540
42%
540
24%
1057
April11th to 20thNight
27%
533
21%
1775
14%
533
40%
533
22%
1102
April21st to endNight
24%
540
19%
1800
9%
540
39%
540
20%
1160
May1st to 10thNight
33%
540
15%
1760
9%
540
42%
540
23%
1112
May11th to 20thNight
39%
531
19%
1427
13%
531
43%
531
27%
965
May21st to endNight
45%
584
18%
1551
9%
582
51%
582
29%
1033
June1st to 10thNight
59%
540
19%
1440
14%
540
62%
540
39%
876
June11th to 20thNight
56%
540
26%
1440
15%
540
62%
540
42%
841
June21st to endNight
57%
540
25%
1440
15%
540
63%
540
46%
812
July1st to 10thNight
66%
525
19%
1400
14%
525
68%
525
38%
866
July11th to 20thNight
66%
522
23%
1400
18%
522
70%
522
47%
772
July21st to endNight
65%
591
23%
1673
22%
558
68%
558
36%
973
August1st to 10thNight
70%
537
23%
1601
24%
534
73%
534
39%
898
August11th to 20thNight
69%
534
24%
1734
27%
534
72%
534
36%
955
August21st to endNight
71%
594
25%
1980
28%
594
74%
594
38%
1036
September1st to 10thNight
59%
540
25%
1800
25%
540
64%
540
33%
1003
September11th to 20thNight
60%
540
34%
1800
31%
540
67%
540
33%
1001
September21st to endNight
55%
686
30%
2013
21%
686
62%
686
37%
1131
October1st to 10thNight
49%
720
27%
2160
18%
720
55%
720
39%
1178
October11th to 20thNight
33%
720
29%
2160
15%
720
45%
720
30%
1278
October21st to endNight
26%
792
23%
2376
11%
792
38%
792
24%
1495
November1st to 10thNight
32%
740
28%
2368
14%
740
48%
740
31%
1312
November11th to 20thNight
28%
760
27%
2470
14%
760
44%
760
25%
1449
November21st to endNight
24%
888
21%
2598
9%
888
36%
888
24%
1675
December1st to 10thNight
24%
950
18%
2660
7%
950
34%
950
21%
1830
December11th to 20thNight
25%
949
19%
3159
7%
948
34%
948
18%
2096
December21st to endNight
16%
1042
10%
4867
5%
1026
27%
1026
8%
3823

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%7%36%5%345%5%7%43%
74698
Night
13%8%35%5%3445%6%44%
75011
TransparencyDay
40%6%12%24%16%3
74410
Night
40%6%11%24%17%3
74819
SeeingDay
17%13%28%25%13%3
14460
Night
18%13%30%27%11%1
24411

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
11%11%48%6%33437%39%
1517
11th to 20thDay
14%10%5%8%6%35%5%5%6%34%
1616
21st to endDay
13%10%5%7%5%35%45%7%38%
1782
February1st to 10thDay
16%10%6%8%5%345%45%34%
1620
11th to 20thDay
14%9%5%6%6%35%446%38%
1682
21st to endDay
15%11%47%5%3445%5%38%
1480
March1st to 10thDay
14%9%46%6%24346%41%
1885
11th to 20thDay
19%9%47%5%34446%35%
1980
21st to endDay
20%12%47%6%35%45%6%29%
2252
April1st to 10thDay
11%6%35%7%45%5%47%44%
2160
11th to 20thDay
17%9%35%4345%45%41%
2134
21st to endDay
20%7%36%5%35%447%36%
2160
May1st to 10thDay
17%8%35%6%35%5%5%8%36%
2196
11th to 20thDay
16%5%35%5%3446%7%41%
2466
21st to endDay
11%6%35%6%36%7%6%8%38%
2725
June1st to 10thDay
8%4245%35%5%7%9%47%
2520
11th to 20thDay
7%425%4445%6%10%49%
2520
21st to endDay
43245%46%7%7%11%47%
2520
July1st to 10thDay
10%3245%45%6%8%10%44%
2520
11th to 20thDay
5%314435%5%7%10%51%
2508
21st to endDay
9%425%5%35%6%7%9%44%
2546
August1st to 10thDay
7%425%6%46%7%7%9%43%
2328
11th to 20thDay
9%5%26%5%36%7%7%9%41%
2165
21st to endDay
7%5%25%43445%7%53%
2376
September1st to 10thDay
12%5%244245%6%9%48%
2160
11th to 20thDay
10%5%2443345%7%52%
2160
21st to endDay
8%425%425%5%5%7%54%
1922
October1st to 10thDay
10%425%5%33447%53%
1800
11th to 20thDay
16%6%34323445%51%
1800
21st to endDay
18%8%3443334447%
1980
November1st to 10thDay
12%5%3342335%6%55%
1708
11th to 20thDay
13%7%35%5%2336%7%47%
1710
21st to endDay
16%10%36%423345%44%
1579
December1st to 10thDay
13%11%46%434346%41%
1520
11th to 20thDay
14%10%47%5%33446%41%
1918
21st to endDay
18%14%5%9%6%45%445%25%
2783
January1st to 10thNight
13%9%46%6%34445%40%
2648
11th to 20thNight
15%9%46%6%34436%38%
2353
21st to endNight
13%10%5%7%6%35%5%46%37%
2574
February1st to 10thNight
15%11%5%8%5%24446%35%
2340
11th to 20thNight
16%8%47%5%2445%6%41%
2164
21st to endNight
17%9%47%6%33345%39%
1776
March1st to 10thNight
16%10%345%23335%44%
2089
11th to 20thNight
18%8%46%5%3445%6%37%
1980
21st to endNight
20%11%47%6%35%5%6%6%29%
2102
April1st to 10thNight
10%7%46%42345%7%48%
1800
11th to 20thNight
14%7%26%5%24447%44%
1775
21st to endNight
19%6%25%5%2445%6%41%
1800
May1st to 10thNight
15%6%25%5%3445%7%44%
1760
11th to 20thNight
14%8%25%5%35%437%43%
1426
21st to endNight
11%5%35%5%45%5%7%9%42%
1551
June1st to 10thNight
7%5%235%35%5%6%8%51%
1440
11th to 20thNight
7%424435%45%9%53%
1440
21st to endNight
5%2235%335%7%9%56%
1440
July1st to 10thNight
9%4245%345%5%11%50%
1440
11th to 20thNight
5%32343445%11%56%
1448
21st to endNight
6%415%5%45%46%9%50%
1772
August1st to 10thNight
7%3145%4446%10%51%
1611
11th to 20thNight
7%425%4345%5%8%53%
1734
21st to endNight
6%3145%3445%9%56%
1980
September1st to 10thNight
13%5%2442345%6%54%
1800
11th to 20thNight
8%5%2443446%6%53%
1800
21st to endNight
7%42443445%5%58%
2013
October1st to 10thNight
9%32442435%6%58%
2160
11th to 20thNight
14%5%25%42335%7%51%
2160
21st to endNight
19%6%34324345%48%
2376
November1st to 10thNight
9%6%25%423445%57%
2368
11th to 20thNight
13%6%35%5%23346%50%
2470
21st to endNight
17%9%25%32335%5%45%
2598
December1st to 10thNight
14%11%46%6%345%5%7%36%
2660
11th to 20thNight
17%9%36%5%3345%5%40%
3279
21st to endNight
18%19%6%9%6%3443423%
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
47%5%11%21%15%2
1518
11th to 20thDay
50%5%11%25%8%
1616
21st to endDay
46%5%14%22%12%2
1782
February1st to 10thDay
53%5%10%21%11%1
1620
11th to 20thDay
47%5%12%19%13%4
1691
21st to endDay
48%48%23%12%4
1480
March1st to 10thDay
46%5%9%23%15%3
1885
11th to 20thDay
52%5%10%18%13%3
1980
21st to endDay
57%5%10%17%9%1
2252
April1st to 10thDay
39%6%12%25%18%1
2160
11th to 20thDay
46%5%9%23%14%3
2134
21st to endDay
49%6%11%21%13%1
2160
May1st to 10thDay
46%8%13%22%10%1
2196
11th to 20thDay
41%9%12%22%15%2
2470
21st to endDay
41%9%14%20%13%2
2725
June1st to 10thDay
32%9%13%28%16%2
2520
11th to 20thDay
30%7%13%27%19%4
2520
21st to endDay
27%10%18%25%15%5%
2520
July1st to 10thDay
32%10%16%27%12%4
2451
11th to 20thDay
25%9%17%27%18%3
2433
21st to endDay
34%9%14%28%14%2
2405
August1st to 10thDay
35%9%15%26%14%1
2314
11th to 20thDay
37%9%12%26%15%1
2165
21st to endDay
31%7%13%24%20%5%
2376
September1st to 10thDay
33%6%12%27%18%4
2160
11th to 20thDay
31%5%8%27%26%2
2160
21st to endDay
29%7%10%28%24%3
1922
October1st to 10thDay
31%5%10%25%24%4
1800
11th to 20thDay
36%49%24%22%5%
1800
21st to endDay
41%49%25%17%3
1980
November1st to 10thDay
31%414%25%21%5%
1708
11th to 20thDay
38%49%23%21%4
1710
21st to endDay
44%49%27%16%
1579
December1st to 10thDay
44%5%11%27%12%1
1520
11th to 20thDay
45%412%22%15%2
1915
21st to endDay
59%6%10%15%9%1
2783
January1st to 10thNight
46%5%10%23%15%1
2648
11th to 20thNight
50%5%9%24%11%1
2353
21st to endNight
47%6%12%22%11%1
2574
February1st to 10thNight
51%6%10%20%12%1
2340
11th to 20thNight
46%5%10%21%16%3
2165
21st to endNight
48%410%21%13%3
1776
March1st to 10thNight
45%49%23%17%3
2089
11th to 20thNight
48%6%9%22%12%3
1980
21st to endNight
55%6%11%19%8%1
2102
April1st to 10thNight
36%5%12%26%18%3
1800
11th to 20thNight
40%6%10%23%16%5%
1775
21st to endNight
44%6%9%23%17%1
1800
May1st to 10thNight
40%7%15%21%16%1
1760
11th to 20thNight
41%7%13%22%15%2
1427
21st to endNight
37%9%16%18%16%3
1552
June1st to 10thNight
29%8%15%28%17%3
1440
11th to 20thNight
26%7%12%28%23%4
1440
21st to endNight
22%8%17%29%18%7%
1440
July1st to 10thNight
30%8%14%29%14%5%
1400
11th to 20thNight
23%7%16%28%24%3
1400
21st to endNight
29%8%12%32%18%1
1673
August1st to 10thNight
26%7%16%33%15%2
1601
11th to 20thNight
28%6%13%29%21%1
1734
21st to endNight
25%7%15%25%23%6%
1980
September1st to 10thNight
32%5%10%25%22%6%
1800
11th to 20thNight
31%6%9%24%27%4
1800
21st to endNight
28%6%9%25%28%4
2013
October1st to 10thNight
27%5%12%25%26%5%
2160
11th to 20thNight
34%48%27%20%6%
2160
21st to endNight
40%49%21%21%4
2376
November1st to 10thNight
31%5%12%26%21%6%
2368
11th to 20thNight
36%48%25%22%4
2470
21st to endNight
42%411%24%17%2
2598
December1st to 10thNight
46%6%11%24%12%1
2660
11th to 20thNight
47%410%23%16%1
3281
21st to endNight
63%7%9%13%7%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
26%27%31%13%3
270
11th to 20thDay
32%23%33%12%
240
21st to endDay
20%31%37%11%1
264
February1st to 10thDay
30%27%32%10%1
240
11th to 20thDay
35%25%27%12%1
240
21st to endDay
33%22%37%7%2
198
March1st to 10thDay
23%31%38%7%1
240
11th to 20thDay
34%22%31%11%11
240
21st to endDay
36%24%27%12%1
338
April1st to 10thDay
20%18%38%18%41
420
11th to 20thDay
27%19%30%17%6%
412
21st to endDay
26%19%33%17%5%
420
May1st to 10thDay
22%18%35%18%6%
459
11th to 20thDay
18%16%30%24%9%1
625
21st to endDay
13%11%33%26%12%4
679
June1st to 10thDay
9%7%26%35%18%5%
630
11th to 20thDay
9%5%29%37%17%3
630
21st to endDay
5%9%34%35%14%3
630
July1st to 10thDay
10%418%31%28%10%
621
11th to 20thDay
5%6%26%37%22%4
618
21st to endDay
8%5%20%35%28%4
684
August1st to 10thDay
9%418%41%23%5%
626
11th to 20thDay
12%423%32%24%6%
479
21st to endDay
10%220%30%30%7%
495
September1st to 10thDay
12%6%18%34%23%6%
450
11th to 20thDay
8%5%21%32%24%10%
450
21st to endDay
10%9%22%34%18%6%
378
October1st to 10thDay
14%12%35%27%10%2
270
11th to 20thDay
24%20%34%18%4
270
21st to endDay
34%21%29%14%2
297
November1st to 10thDay
16%14%40%19%8%3
270
11th to 20thDay
24%19%29%21%42
270
21st to endDay
28%19%30%20%21
270
December1st to 10thDay
18%26%34%13%7%2
270
11th to 20thDay
25%19%36%16%3
270
21st to endDay
27%28%32%10%2
297
January1st to 10thNight
21%22%34%19%4
950
11th to 20thNight
24%21%35%17%3
905
21st to endNight
21%21%37%19%1
990
February1st to 10thNight
25%19%36%18%2
900
11th to 20thNight
24%20%36%17%2
769
21st to endNight
26%21%35%16%2
592
March1st to 10thNight
25%17%38%18%3
649
11th to 20thNight
24%13%37%21%4
540
21st to endNight
26%17%36%18%3
594
April1st to 10thNight
18%21%34%23%41
540
11th to 20thNight
21%16%34%24%6%
533
21st to endNight
22%13%38%22%5%
540
May1st to 10thNight
16%13%34%29%8%
540
11th to 20thNight
17%10%29%30%13%1
531
21st to endNight
12%8%29%31%18%2
584
June1st to 10thNight
10%322%41%23%2
540
11th to 20thNight
9%228%41%20%1
540
21st to endNight
3430%43%19%1
540
July1st to 10thNight
11%213%38%31%5%
525
11th to 20thNight
6%220%41%29%3
522
21st to endNight
7%218%42%30%2
591
August1st to 10thNight
8%312%46%30%2
537
11th to 20thNight
7%316%41%31%3
534
21st to endNight
6%216%39%34%3
594
September1st to 10thNight
14%317%37%24%5%
540
11th to 20thNight
10%420%33%28%4
540
21st to endNight
9%7%25%32%23%4
686
October1st to 10thNight
10%7%30%28%22%3
720
11th to 20thNight
17%16%32%26%8%1
720
21st to endNight
23%16%33%21%7%
792
November1st to 10thNight
13%14%38%25%10%
740
11th to 20thNight
20%17%32%23%7%
760
21st to endNight
23%18%32%21%5%
888
December1st to 10thNight
23%18%33%21%5%1
950
11th to 20thNight
25%15%31%26%3
950
21st to endNight
28%20%32%18%2
1045
Page generated at 2024-01-08 10:14:18. Version ac07

Copyright 2024 Attilla Danko


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