Morgan Point Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Morgan Point Observatory clear sky chart from 2005-11-06 to 2024-01-22.

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
40%
24273
23%
74820
14%
24210
50%
24210
27%
45283

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
23%
950
25%
2458
7%
946
37%
946
24%
1595
January11th to 20thNight
20%
950
25%
2470
7%
950
32%
950
24%
1599
January21st to endNight
23%
1000
27%
2600
7%
1000
36%
1000
28%
1631
February1st to 10thNight
20%
900
19%
2340
4%
900
28%
900
21%
1610
February11th to 20thNight
16%
824
19%
2219
4%
820
26%
820
21%
1453
February21st to endNight
18%
530
24%
1714
7%
530
34%
530
18%
1088
March1st to 10thNight
30%
540
23%
1980
14%
540
41%
540
19%
1206
March11th to 20thNight
25%
540
18%
1980
12%
540
35%
540
17%
1284
March21st to endNight
25%
594
16%
2178
9%
594
35%
594
16%
1432
April1st to 10thNight
28%
540
23%
1829
12%
540
44%
540
22%
1068
April11th to 20thNight
32%
533
25%
1775
17%
533
47%
533
23%
1064
April21st to endNight
27%
540
20%
1800
10%
540
43%
540
21%
1135
May1st to 10thNight
38%
540
18%
1716
13%
540
47%
540
26%
1065
May11th to 20thNight
45%
531
20%
1593
18%
531
50%
531
29%
980
May21st to endNight
47%
584
17%
1746
12%
582
54%
582
25%
1142
June1st to 10thNight
64%
540
23%
1472
19%
540
68%
540
42%
828
June11th to 20thNight
63%
540
26%
1440
18%
540
70%
540
49%
786
June21st to endNight
67%
540
26%
1568
22%
540
72%
540
47%
823
July1st to 10thNight
71%
525
17%
1575
18%
525
73%
525
36%
905
July11th to 20thNight
77%
522
23%
1566
23%
522
80%
522
47%
810
July21st to endNight
75%
591
25%
1673
27%
558
78%
558
38%
947
August1st to 10thNight
72%
537
20%
1601
21%
534
74%
534
36%
920
August11th to 20thNight
69%
534
23%
1691
26%
534
72%
534
35%
963
August21st to endNight
74%
594
24%
1980
28%
594
75%
594
37%
1073
September1st to 10thNight
72%
540
26%
1800
27%
540
75%
540
39%
943
September11th to 20thNight
65%
540
28%
1849
28%
540
69%
540
30%
1067
September21st to endNight
64%
598
30%
2038
27%
598
69%
598
37%
1050
October1st to 10thNight
57%
720
28%
2160
20%
720
62%
720
42%
1153
October11th to 20thNight
38%
720
32%
2160
16%
720
52%
720
34%
1218
October21st to endNight
35%
792
28%
2376
16%
792
46%
792
28%
1432
November1st to 10thNight
36%
740
31%
2220
15%
740
51%
740
34%
1236
November11th to 20thNight
37%
760
30%
2329
16%
760
52%
760
32%
1316
November21st to endNight
30%
903
24%
2613
12%
903
42%
903
26%
1610
December1st to 10thNight
27%
950
24%
2660
8%
950
40%
950
26%
1685
December11th to 20thNight
28%
949
23%
3134
10%
948
38%
948
19%
2052
December21st to endNight
23%
1042
15%
4517
7%
1026
35%
1026
12%
3114

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
11%6%35%5%35%5%5%7%45%
74671
Night
10%6%35%43445%7%50%
75273
TransparencyDay
39%7%11%22%17%4
74394
Night
35%6%11%24%20%5%
75070
SeeingDay
15%14%27%24%15%4
14314
Night
15%14%27%27%15%2
24277

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%8%35%424336%49%
1707
11th to 20thDay
11%7%35%5%35%445%46%
1710
21st to endDay
12%8%3442346%5%49%
1791
February1st to 10thDay
14%10%35%5%33445%44%
1620
11th to 20thDay
11%8%37%6%35%446%42%
1628
21st to endDay
16%9%47%5%34346%39%
1558
March1st to 10thDay
12%8%35%5%34446%45%
1980
11th to 20thDay
18%8%35%5%34445%41%
1980
21st to endDay
16%9%36%5%445%46%38%
2178
April1st to 10thDay
9%6%25%6%35%6%6%6%45%
2129
11th to 20thDay
15%6%35%5%35%5%5%7%41%
2134
21st to endDay
17%8%36%6%345%45%40%
2160
May1st to 10thDay
15%7%36%6%45%5%5%6%39%
2240
11th to 20thDay
14%6%35%6%35%5%5%7%41%
2302
21st to endDay
10%6%36%6%46%7%7%9%36%
2531
June1st to 10thDay
9%425%5%37%5%7%9%43%
2484
11th to 20thDay
5%425%6%5%7%7%7%9%45%
2520
21st to endDay
43245%36%6%7%11%49%
2381
July1st to 10thDay
8%5%36%7%47%7%7%10%36%
2340
11th to 20thDay
4425%5%48%7%7%9%45%
2340
21st to endDay
7%5%35%5%5%6%6%8%11%41%
2546
August1st to 10thDay
8%5%26%6%46%6%8%10%39%
2328
11th to 20thDay
11%4246%36%6%6%9%43%
2208
21st to endDay
6%425%6%45%6%7%8%47%
2376
September1st to 10thDay
12%5%25%43445%6%49%
2160
11th to 20thDay
12%425%5%345%6%7%46%
2107
21st to endDay
9%42443446%6%54%
1904
October1st to 10thDay
8%5%245%335%5%5%55%
1800
11th to 20thDay
11%6%25%433236%56%
1800
21st to endDay
18%6%14323345%50%
1980
November1st to 10thDay
9%5%2442335%5%58%
1858
11th to 20thDay
8%7%24433447%53%
1847
21st to endDay
13%6%35%5%34447%46%
1563
December1st to 10thDay
12%8%235%3445%8%47%
1520
11th to 20thDay
10%8%36%6%35%445%47%
1918
21st to endDay
10%14%5%7%5%35%5%6%5%35%
3043
January1st to 10thNight
12%6%25%4345%5%6%48%
2458
11th to 20thNight
11%8%36%5%33347%49%
2470
21st to endNight
12%6%35%334345%53%
2600
February1st to 10thNight
14%8%46%5%34447%42%
2340
11th to 20thNight
13%8%35%42345%7%45%
2218
21st to endNight
13%8%37%424446%45%
1714
March1st to 10thNight
13%7%35%43445%7%44%
1980
11th to 20thNight
17%10%35%424347%41%
1980
21st to endNight
14%9%36%5%35%45%6%40%
2178
April1st to 10thNight
9%5%245%35%46%7%51%
1829
11th to 20thNight
12%7%2443445%6%48%
1775
21st to endNight
15%5%35%43446%7%44%
1800
May1st to 10thNight
11%5%245%345%5%8%48%
1716
11th to 20thNight
15%6%13424448%49%
1593
21st to endNight
8%6%346%45%6%7%10%42%
1745
June1st to 10thNight
7%3142245%6%9%56%
1472
11th to 20thNight
441332437%12%58%
1440
21st to endNight
3214325%45%10%60%
1568
July1st to 10thNight
5%4245%35%5%7%10%51%
1620
11th to 20thNight
421333446%9%62%
1620
21st to endNight
5%3245%25%6%7%9%52%
1772
August1st to 10thNight
5%3245%45%6%7%11%49%
1611
11th to 20thNight
5%5%245%35%5%7%9%51%
1691
21st to endNight
6%314435%46%9%54%
1980
September1st to 10thNight
8%42342446%8%57%
1800
11th to 20thNight
11%5%245%2445%6%51%
1849
21st to endNight
7%5%13423347%60%
2038
October1st to 10thNight
6%42432345%7%61%
2160
11th to 20thNight
12%5%23323345%58%
2160
21st to endNight
15%6%2432334454%
2376
November1st to 10thNight
10%424333345%59%
2220
11th to 20thNight
11%5%2342345%6%56%
2329
21st to endNight
13%6%23424447%50%
2613
December1st to 10thNight
12%7%35%424446%49%
2660
11th to 20thNight
11%8%37%5%345%5%5%45%
3279
21st to endNight
12%10%7%7%7%34445%36%
4619

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
38%48%24%20%5%
1708
11th to 20thDay
41%5%7%24%20%2
1710
21st to endDay
37%49%27%18%5%
1791
February1st to 10thDay
45%5%10%21%16%4
1620
11th to 20thDay
44%6%8%20%17%4
1637
21st to endDay
48%5%7%16%15%9%
1558
March1st to 10thDay
41%5%8%18%19%10%
1980
11th to 20thDay
46%6%8%20%15%5%
1980
21st to endDay
48%6%10%20%13%2
2178
April1st to 10thDay
39%8%10%21%19%2
2129
11th to 20thDay
43%7%10%19%16%5%
2134
21st to endDay
47%6%8%21%15%2
2160
May1st to 10thDay
48%7%10%20%15%2
2240
11th to 20thDay
43%8%13%22%12%1
2306
21st to endDay
44%10%12%21%11%1
2531
June1st to 10thDay
36%9%15%26%13%1
2484
11th to 20thDay
34%10%15%26%14%2
2520
21st to endDay
28%10%14%27%17%4
2381
July1st to 10thDay
39%12%15%21%12%1
2276
11th to 20thDay
31%9%16%26%16%3
2271
21st to endDay
35%10%16%28%10%1
2405
August1st to 10thDay
36%11%18%25%11%
2314
11th to 20thDay
37%9%12%26%15%1
2208
21st to endDay
33%9%16%22%15%5%
2376
September1st to 10thDay
36%7%10%22%17%7%
2160
11th to 20thDay
35%7%9%21%23%4
2107
21st to endDay
31%6%9%24%26%5%
1904
October1st to 10thDay
31%6%11%23%23%7%
1800
11th to 20thDay
33%36%24%25%8%
1800
21st to endDay
39%5%7%24%18%7%
1980
November1st to 10thDay
31%49%26%22%8%
1858
11th to 20thDay
33%6%8%21%24%9%
1847
21st to endDay
41%48%17%24%5%
1563
December1st to 10thDay
38%5%9%25%18%5%
1520
11th to 20thDay
42%5%6%16%28%3
1915
21st to endDay
49%6%9%17%15%4
3043
January1st to 10thNight
37%6%8%21%23%4
2458
11th to 20thNight
38%49%24%20%3
2470
21st to endNight
36%49%26%21%5%
2600
February1st to 10thNight
44%5%9%21%16%4
2340
11th to 20thNight
40%5%9%23%17%5%
2219
21st to endNight
42%5%8%19%18%9%
1714
March1st to 10thNight
41%5%8%16%20%10%
1980
11th to 20thNight
45%6%8%19%17%4
1980
21st to endNight
46%6%9%23%14%2
2178
April1st to 10thNight
34%7%11%22%20%5%
1829
11th to 20thNight
37%5%8%25%19%6%
1775
21st to endNight
40%8%10%26%15%2
1800
May1st to 10thNight
37%8%14%22%18%2
1716
11th to 20thNight
34%8%15%24%16%2
1594
21st to endNight
37%11%16%23%12%1
1746
June1st to 10thNight
25%7%16%33%17%2
1472
11th to 20thNight
20%7%16%36%18%3
1440
21st to endNight
21%7%16%27%23%6%
1568
July1st to 10thNight
26%10%20%24%19%1
1575
11th to 20thNight
21%6%17%32%21%3
1566
21st to endNight
26%9%15%36%14%1
1673
August1st to 10thNight
27%10%19%33%11%
1601
11th to 20thNight
27%9%17%24%20%2
1691
21st to endNight
26%8%15%28%18%5%
1980
September1st to 10thNight
26%6%13%31%18%7%
1800
11th to 20thNight
33%7%11%20%25%4
1849
21st to endNight
26%6%10%22%30%6%
2038
October1st to 10thNight
24%6%14%24%23%9%
2160
11th to 20thNight
30%48%20%31%7%
2160
21st to endNight
37%37%22%21%9%
2376
November1st to 10thNight
30%410%24%25%8%
2220
11th to 20thNight
30%5%8%23%26%8%
2329
21st to endNight
37%5%8%21%24%5%
2613
December1st to 10thNight
38%5%9%22%21%5%
2660
11th to 20thNight
42%5%6%20%21%5%
3281
21st to endNight
51%5%8%18%15%3
4619

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%25%31%16%3
270
11th to 20thDay
26%32%31%9%2
270
21st to endDay
22%30%33%12%3
267
February1st to 10thDay
26%28%34%10%2
240
11th to 20thDay
29%35%26%8%2
240
21st to endDay
39%30%24%6%2
198
March1st to 10thDay
26%25%33%13%3
240
11th to 20thDay
34%24%30%11%1
240
21st to endDay
27%37%26%7%2
264
April1st to 10thDay
17%28%33%15%6%1
389
11th to 20thDay
23%24%30%17%5%
412
21st to endDay
23%24%31%16%5%2
420
May1st to 10thDay
18%20%38%17%7%
503
11th to 20thDay
16%14%34%23%10%2
625
21st to endDay
11%11%38%23%12%4
679
June1st to 10thDay
10%7%22%33%22%6%
630
11th to 20thDay
5%430%36%22%3
630
21st to endDay
46%31%35%19%5%
630
July1st to 10thDay
8%419%30%32%8%
621
11th to 20thDay
5%221%35%27%10%
618
21st to endDay
6%313%37%30%12%
684
August1st to 10thDay
8%218%39%27%5%
626
11th to 20thDay
11%215%36%29%7%
522
21st to endDay
9%312%31%33%13%
495
September1st to 10thDay
11%5%14%30%33%8%
450
11th to 20thDay
9%316%38%26%9%
397
21st to endDay
11%9%27%28%22%3
270
October1st to 10thDay
8%13%32%30%15%2
270
11th to 20thDay
15%19%43%16%7%1
270
21st to endDay
31%15%31%17%5%1
297
November1st to 10thDay
14%20%36%19%8%3
270
11th to 20thDay
18%23%35%19%42
270
21st to endDay
25%23%28%18%5%1
270
December1st to 10thDay
18%31%30%15%42
270
11th to 20thDay
23%26%31%13%6%
270
21st to endDay
24%28%34%11%2
297
January1st to 10thNight
19%22%32%23%3
950
11th to 20thNight
19%27%32%18%4
950
21st to endNight
17%23%34%22%4
1000
February1st to 10thNight
21%21%35%20%3
900
11th to 20thNight
21%25%35%17%1
824
21st to endNight
23%25%32%18%1
530
March1st to 10thNight
21%19%28%28%4
540
11th to 20thNight
25%15%32%25%3
540
21st to endNight
21%19%34%21%6%
594
April1st to 10thNight
15%23%31%26%5%
540
11th to 20thNight
17%20%29%26%8%
533
21st to endNight
17%19%34%23%7%1
540
May1st to 10thNight
13%12%35%31%9%
540
11th to 20thNight
17%10%25%30%17%1
531
21st to endNight
9%8%31%28%20%4
584
June1st to 10thNight
7%6%17%34%35%2
540
11th to 20thNight
5%325%36%28%3
540
21st to endNight
3321%39%31%4
540
July1st to 10thNight
4213%32%40%9%
525
11th to 20thNight
3113%35%39%9%
522
21st to endNight
5%19%38%36%9%
591
August1st to 10thNight
6%112%38%38%7%
537
11th to 20thNight
8%214%35%37%5%
534
21st to endNight
5%211%35%39%8%
594
September1st to 10thNight
9%212%33%41%3
540
11th to 20thNight
13%112%35%32%6%
540
21st to endNight
10%5%17%32%32%4
598
October1st to 10thNight
9%6%24%32%27%3
720
11th to 20thNight
14%14%30%28%13%
720
21st to endNight
21%15%27%25%11%1
792
November1st to 10thNight
13%14%34%25%13%1
740
11th to 20thNight
14%16%30%32%8%
760
21st to endNight
19%18%30%24%8%
903
December1st to 10thNight
20%16%35%23%6%
950
11th to 20thNight
20%18%31%25%5%
950
21st to endNight
20%24%29%22%4
1045
Page generated at 2024-01-19 08:28:32. Version ac07

Copyright 2024 Attilla Danko


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