Monroe Robotic Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Monroe Robotic Observatory clear sky chart from 2005-11-06 to 2024-01-14.

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
44%
24093
19%
74262
12%
24035
52%
24035
19%
51491

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
34%
948
20%
2458
7%
946
43%
946
19%
1794
January11th to 20thNight
30%
920
19%
2392
6%
920
39%
920
18%
1763
January21st to endNight
34%
990
21%
2574
8%
990
41%
990
17%
1939
February1st to 10thNight
24%
806
17%
2246
5%
806
33%
806
16%
1672
February11th to 20thNight
24%
704
16%
2098
4%
700
33%
700
14%
1547
February21st to endNight
20%
592
21%
1776
5%
592
34%
592
15%
1264
March1st to 10thNight
28%
549
19%
1989
8%
549
40%
549
14%
1380
March11th to 20thNight
26%
540
18%
1980
9%
540
38%
540
13%
1403
March21st to endNight
29%
594
15%
2178
6%
594
41%
594
12%
1558
April1st to 10thNight
25%
540
16%
1980
7%
540
38%
540
14%
1351
April11th to 20thNight
29%
533
19%
1855
10%
533
43%
533
16%
1270
April21st to endNight
29%
540
19%
1620
8%
540
42%
540
17%
1159
May1st to 10thNight
35%
540
17%
1620
8%
540
46%
540
16%
1191
May11th to 20thNight
36%
531
15%
1594
12%
531
43%
531
18%
1146
May21st to endNight
48%
584
16%
1745
11%
582
58%
582
19%
1239
June1st to 10thNight
65%
540
16%
1620
14%
540
71%
540
23%
1091
June11th to 20thNight
61%
540
20%
1620
19%
540
66%
540
26%
1061
June21st to endNight
67%
540
21%
1620
20%
540
72%
540
25%
1079
July1st to 10thNight
74%
525
16%
1575
17%
525
76%
525
22%
1102
July11th to 20thNight
78%
522
21%
1566
22%
522
84%
522
27%
1021
July21st to endNight
82%
591
20%
1673
23%
558
84%
558
25%
1124
August1st to 10thNight
81%
537
24%
1601
25%
534
84%
534
29%
1018
August11th to 20thNight
73%
534
26%
1600
26%
534
77%
534
25%
1063
August21st to endNight
81%
594
18%
2008
23%
594
81%
594
21%
1339
September1st to 10thNight
73%
540
18%
1980
20%
540
75%
540
18%
1318
September11th to 20thNight
66%
540
17%
1980
18%
540
68%
540
15%
1422
September21st to endNight
67%
540
27%
1980
24%
540
74%
540
25%
1185
October1st to 10thNight
57%
555
25%
1995
21%
555
63%
555
20%
1307
October11th to 20thNight
46%
720
25%
2160
12%
720
56%
720
21%
1463
October21st to endNight
40%
792
21%
2376
10%
792
48%
792
20%
1643
November1st to 10thNight
45%
740
23%
2220
10%
740
55%
740
23%
1495
November11th to 20thNight
41%
944
22%
2464
10%
944
48%
944
22%
1728
November21st to endNight
32%
950
18%
2470
7%
950
38%
950
18%
1849
December1st to 10thNight
34%
950
21%
2470
8%
950
42%
950
20%
1785
December11th to 20thNight
29%
949
23%
2858
7%
948
37%
948
15%
2046
December21st to endNight
27%
1039
13%
4321
7%
1026
36%
1026
13%
2676

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
10%42443445%7%53%
74932
Night
9%42442345%7%57%
74858
TransparencyDay
20%37%6%15%16%5%
74657
Night
18%36%6%14%18%8%
74653
SeeingDay
13%10%26%29%19%5%
14089
Night
12%9%31%33%14%1
24102

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
12%5%34312345%56%
1707
11th to 20thDay
13%42432235%6%56%
1647
21st to endDay
12%5%24422345%56%
1782
February1st to 10thDay
14%7%25%5%23336%50%
1728
11th to 20thDay
13%6%35%5%44345%49%
1749
21st to endDay
20%7%2431223352%
1480
March1st to 10thDay
13%6%25%42445%5%48%
1970
11th to 20thDay
15%6%25%434345%49%
1980
21st to endDay
13%6%344345%46%48%
2178
April1st to 10thDay
11%5%24424446%54%
1980
11th to 20thDay
12%425%43445%7%49%
2048
21st to endDay
11%5%245%3445%6%49%
2340
May1st to 10thDay
12%5%35%5%2345%6%50%
2340
11th to 20thDay
12%6%25%4345%5%9%45%
2302
21st to endDay
10%5%36%6%45%5%6%9%40%
2531
June1st to 10thDay
5%425%6%35%5%6%8%51%
2340
11th to 20thDay
6%3244345%6%8%54%
2340
21st to endDay
5%323435%46%8%58%
2340
July1st to 10thDay
6%325%6%5%6%6%7%11%43%
2340
11th to 20thDay
4213335%5%5%9%60%
2340
21st to endDay
4213446%7%7%10%52%
2546
August1st to 10thDay
3314435%5%6%7%59%
2328
11th to 20thDay
6%3245%445%6%9%50%
2301
21st to endDay
43125%35%6%7%11%53%
2344
September1st to 10thDay
9%323424448%57%
1980
11th to 20thDay
12%5%25%5%3446%7%47%
1980
21st to endDay
8%32332345%8%59%
1980
October1st to 10thDay
6%314434446%61%
1944
11th to 20thDay
11%413223235%64%
1800
21st to endDay
14%5%2422223460%
1980
November1st to 10thDay
11%424332335%60%
1858
11th to 20thDay
6%323323336%65%
1713
21st to endDay
13%6%2432323457%
1710
December1st to 10thDay
12%5%25%42345%7%51%
1710
11th to 20thDay
13%7%35%5%23435%48%
2161
21st to endDay
16%7%24424445%49%
3135
January1st to 10thNight
10%323324447%57%
2458
11th to 20thNight
12%5%23323335%59%
2392
21st to endNight
10%434423345%58%
2574
February1st to 10thNight
12%6%345%2334454%
2246
11th to 20thNight
13%6%34324445%52%
2098
21st to endNight
14%6%35%42334453%
1776
March1st to 10thNight
14%42444345%6%49%
1989
11th to 20thNight
14%424423446%52%
1980
21st to endNight
9%5%24434347%54%
2178
April1st to 10thNight
9%42442445%9%53%
1980
11th to 20thNight
11%5%14424446%54%
1855
21st to endNight
10%425%32345%7%54%
1620
May1st to 10thNight
9%5%245%2346%8%53%
1620
11th to 20thNight
11%5%2442425%9%51%
1593
21st to endNight
8%3144245%6%11%52%
1745
June1st to 10thNight
43134245%6%10%60%
1620
11th to 20thNight
421332446%10%61%
1620
21st to endNight
211233345%9%66%
1620
July1st to 10thNight
43234345%7%13%52%
1620
11th to 20thNight
211222436%9%68%
1620
21st to endNight
12133235%8%10%61%
1772
August1st to 10thNight
221232235%10%68%
1611
11th to 20thNight
6%21342346%10%58%
1600
21st to endNight
321442446%11%59%
2008
September1st to 10thNight
8%31332435%6%61%
1980
11th to 20thNight
9%5%25%5%34447%52%
1980
21st to endNight
6%21332335%7%65%
1980
October1st to 10thNight
6%323424347%62%
1995
11th to 20thNight
10%41332334464%
2160
21st to endNight
14%5%2331233462%
2376
November1st to 10thNight
10%413313335%64%
2220
11th to 20thNight
6%423323447%63%
2464
21st to endNight
13%5%24424445%55%
2470
December1st to 10thNight
10%5%24423446%57%
2470
11th to 20thNight
12%5%25%423445%54%
3036
21st to endNight
14%6%34323345%54%
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
18%39%414%20%4
1708
11th to 20thDay
18%41%315%20%4
1647
21st to endDay
22%37%414%17%6%
1782
February1st to 10thDay
26%36%5%14%14%5%
1728
11th to 20thDay
26%37%412%13%8%
1759
21st to endDay
23%35%411%19%8%
1480
March1st to 10thDay
22%36%6%12%15%9%
1970
11th to 20thDay
28%37%5%13%13%4
1980
21st to endDay
27%36%5%13%14%4
2178
April1st to 10thDay
21%37%7%15%13%8%
1980
11th to 20thDay
21%37%6%13%14%9%
2048
21st to endDay
24%38%7%15%14%3
2340
May1st to 10thDay
25%37%6%17%12%3
2340
11th to 20thDay
23%39%9%15%13%1
2306
21st to endDay
26%39%10%14%9%1
2531
June1st to 10thDay
19%39%11%17%12%2
2340
11th to 20thDay
16%38%8%18%17%3
2340
21st to endDay
17%37%7%16%19%4
2340
July1st to 10thDay
22%39%8%17%12%1
2276
11th to 20thDay
14%39%8%17%19%3
2271
21st to endDay
16%40%11%20%12%1
2405
August1st to 10thDay
13%37%9%19%20%3
2314
11th to 20thDay
18%37%9%17%16%3
2301
21st to endDay
18%39%9%17%13%4
2344
September1st to 10thDay
19%37%6%12%17%10%
1980
11th to 20thDay
25%37%6%10%14%7%
1980
21st to endDay
13%35%413%23%11%
1980
October1st to 10thDay
17%36%5%14%15%13%
1944
11th to 20thDay
17%35%311%21%12%
1800
21st to endDay
20%36%5%13%18%9%
1980
November1st to 10thDay
13%41%417%19%7%
1858
11th to 20thDay
13%40%418%19%7%
1713
21st to endDay
20%39%411%17%8%
1710
December1st to 10thDay
19%40%319%15%4
1710
11th to 20thDay
26%32%412%22%4
2159
21st to endDay
28%25%419%19%5%
3135
January1st to 10thNight
16%40%411%22%6%
2458
11th to 20thNight
17%40%411%22%6%
2392
21st to endNight
23%37%311%17%9%
2574
February1st to 10thNight
24%36%5%13%15%7%
2246
11th to 20thNight
24%37%410%18%7%
2098
21st to endNight
21%36%413%15%11%
1776
March1st to 10thNight
21%36%412%14%12%
1989
11th to 20thNight
23%37%7%13%15%6%
1980
21st to endNight
24%37%8%11%16%5%
2178
April1st to 10thNight
19%37%6%13%14%11%
1980
11th to 20thNight
20%36%5%13%15%12%
1855
21st to endNight
21%37%8%15%17%3
1620
May1st to 10thNight
23%37%7%15%13%4
1620
11th to 20thNight
20%38%12%15%14%2
1594
21st to endNight
17%40%13%16%11%3
1746
June1st to 10thNight
13%38%12%20%13%4
1620
11th to 20thNight
11%37%9%21%16%6%
1620
21st to endNight
12%38%6%18%20%7%
1620
July1st to 10thNight
16%38%9%18%16%2
1575
11th to 20thNight
9%39%7%23%18%5%
1566
21st to endNight
11%40%11%20%16%2
1673
August1st to 10thNight
9%36%5%23%22%5%
1601
11th to 20thNight
13%36%8%19%19%5%
1600
21st to endNight
15%37%8%17%18%5%
2008
September1st to 10thNight
18%36%6%11%20%9%
1980
11th to 20thNight
24%37%411%15%9%
1980
21st to endNight
9%35%412%24%15%
1980
October1st to 10thNight
16%36%412%17%15%
1995
11th to 20thNight
16%35%48%21%15%
2160
21st to endNight
18%35%312%19%12%
2376
November1st to 10thNight
11%40%317%20%9%
2220
11th to 20thNight
12%40%415%19%9%
2464
21st to endNight
19%40%5%9%19%8%
2470
December1st to 10thNight
16%39%417%15%8%
2470
11th to 20thNight
23%32%412%22%6%
3037
21st to endNight
25%25%5%16%21%9%
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
21%20%35%20%4
270
11th to 20thDay
24%20%33%16%5%2
249
21st to endDay
16%23%38%16%6%2
264
February1st to 10thDay
23%15%40%19%3
240
11th to 20thDay
27%19%40%11%3
240
21st to endDay
35%22%31%8%4
198
March1st to 10thDay
22%23%34%18%31
240
11th to 20thDay
27%20%39%9%5%1
240
21st to endDay
20%21%42%13%21
264
April1st to 10thDay
21%21%33%21%4
240
11th to 20thDay
19%18%42%16%4
326
21st to endDay
15%20%40%19%6%2
600
May1st to 10thDay
13%12%40%28%6%1
603
11th to 20thDay
17%9%37%24%11%2
625
21st to endDay
14%7%34%30%11%4
679
June1st to 10thDay
6%318%41%25%6%
630
11th to 20thDay
6%325%39%22%5%
630
21st to endDay
4317%40%27%8%
630
July1st to 10thDay
6%211%39%33%10%
621
11th to 20thDay
329%35%42%9%
618
21st to endDay
326%37%41%12%
684
August1st to 10thDay
429%38%37%10%
626
11th to 20thDay
8%19%39%35%7%
615
21st to endDay
5%8%35%40%12%
463
September1st to 10thDay
7%16%33%37%15%
270
11th to 20thDay
7%310%36%32%12%
270
21st to endDay
14%410%42%21%9%
270
October1st to 10thDay
35%31%31%26%5%
270
11th to 20thDay
13%11%32%29%14%1
270
21st to endDay
26%12%26%27%8%1
297
November1st to 10thDay
18%12%36%23%8%3
270
11th to 20thDay
12%15%39%23%8%3
270
21st to endDay
21%19%34%20%5%1
270
December1st to 10thDay
14%16%36%24%7%2
270
11th to 20thDay
20%14%43%17%5%
270
21st to endDay
20%22%37%19%3
297
January1st to 10thNight
14%14%36%29%7%
950
11th to 20thNight
16%15%35%27%6%
920
21st to endNight
12%14%36%31%6%
990
February1st to 10thNight
17%14%40%26%4
806
11th to 20thNight
18%17%40%22%4
704
21st to endNight
20%20%39%20%2
592
March1st to 10thNight
17%15%37%27%4
549
11th to 20thNight
16%13%43%24%5%
540
21st to endNight
13%15%41%26%5%1
594
April1st to 10thNight
12%16%44%24%4
540
11th to 20thNight
14%16%38%28%4
533
21st to endNight
12%12%45%21%9%1
540
May1st to 10thNight
11%10%41%31%7%1
540
11th to 20thNight
13%8%38%28%12%1
531
21st to endNight
8%435%35%16%2
584
June1st to 10thNight
4323%42%26%2
540
11th to 20thNight
4229%49%15%
540
21st to endNight
2124%45%25%3
540
July1st to 10thNight
5%112%44%34%3
525
11th to 20thNight
3114%45%36%2
522
21st to endNight
119%46%38%4
591
August1st to 10thNight
2111%53%31%3
537
11th to 20thNight
8%110%43%34%4
534
21st to endNight
318%49%33%6%
594
September1st to 10thNight
8%211%42%35%3
540
11th to 20thNight
11%113%42%30%4
540
21st to endNight
7%120%42%26%3
540
October1st to 10thNight
8%427%34%24%3
555
11th to 20thNight
13%7%31%36%12%1
720
21st to endNight
18%9%31%30%11%1
792
November1st to 10thNight
11%6%35%35%12%1
740
11th to 20thNight
9%12%35%32%11%1
944
21st to endNight
18%12%35%25%9%
950
December1st to 10thNight
14%13%36%31%6%
950
11th to 20thNight
18%11%37%28%5%
950
21st to endNight
19%13%37%25%6%
1045
Page generated at 2024-01-11 12:32:01. Version ac07

Copyright 2024 Attilla Danko


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