Magdalena Ridge Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Magdalena Ridge Observatory clear sky chart from 2005-11-06 to 2024-01-13.

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
49%
23902
32%
74830
18%
23851
63%
23851
39%
37639

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
42%
758
35%
2457
19%
756
62%
756
41%
1186
January11th to 20thNight
37%
732
35%
2379
20%
732
57%
732
39%
1137
January21st to endNight
40%
792
37%
2574
19%
792
64%
792
39%
1217
February1st to 10thNight
38%
720
34%
2340
16%
720
60%
720
41%
1077
February11th to 20thNight
30%
700
34%
2111
13%
700
52%
700
37%
1078
February21st to endNight
30%
592
39%
1750
13%
592
56%
592
38%
851
March1st to 10thNight
36%
720
37%
1980
14%
720
55%
720
39%
1017
March11th to 20thNight
39%
720
35%
1980
15%
720
56%
720
43%
1013
March21st to endNight
33%
784
36%
2170
10%
784
54%
784
41%
1093
April1st to 10thNight
28%
540
36%
1800
13%
540
56%
540
36%
811
April11th to 20thNight
29%
533
37%
1777
14%
533
58%
533
35%
800
April21st to endNight
28%
540
37%
1800
13%
540
59%
540
36%
832
May1st to 10thNight
36%
540
32%
1800
17%
540
58%
540
42%
840
May11th to 20thNight
47%
531
29%
1685
16%
531
61%
531
40%
870
May21st to endNight
42%
583
34%
1746
17%
582
60%
582
53%
807
June1st to 10thNight
50%
540
27%
1620
17%
540
60%
540
42%
831
June11th to 20thNight
52%
540
30%
1620
19%
540
63%
540
49%
774
June21st to endNight
58%
540
20%
1620
15%
540
64%
540
35%
925
July1st to 10thNight
63%
525
18%
1575
16%
525
65%
525
27%
983
July11th to 20thNight
71%
522
16%
1566
14%
522
72%
522
28%
971
July21st to endNight
70%
591
14%
1674
12%
558
71%
558
26%
1093
August1st to 10thNight
75%
537
15%
1632
14%
534
76%
534
28%
1007
August11th to 20thNight
71%
534
22%
1778
22%
534
73%
534
26%
1095
August21st to endNight
75%
594
22%
1980
24%
594
76%
594
32%
1133
September1st to 10thNight
70%
540
24%
1800
26%
540
71%
540
30%
1062
September11th to 20thNight
72%
540
37%
1800
34%
540
78%
540
40%
935
September21st to endNight
66%
681
32%
2044
22%
681
74%
681
49%
1022
October1st to 10thNight
54%
720
31%
2160
18%
720
64%
720
45%
1105
October11th to 20thNight
56%
720
41%
2160
21%
720
70%
720
59%
956
October21st to endNight
56%
792
42%
2376
24%
792
70%
792
53%
1076
November1st to 10thNight
59%
740
43%
2220
25%
740
74%
740
58%
973
November11th to 20thNight
57%
774
43%
2294
25%
774
71%
774
57%
1001
November21st to endNight
47%
950
38%
2470
19%
950
59%
950
43%
1327
December1st to 10thNight
44%
950
35%
2629
17%
950
59%
950
45%
1364
December11th to 20thNight
38%
949
32%
3132
15%
948
54%
948
31%
1683
December21st to endNight
38%
838
25%
4331
19%
827
59%
827
28%
1694

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
34244345%6%7%58%
74389
Night
342443445%7%61%
75389
TransparencyDay
22%7%8%16%27%21%
74115
Night
21%6%8%17%28%21%
75184
SeeingDay
8%18%28%28%15%3
13228
Night
5%13%27%33%19%3
23918

By Month

Percentage Cloud Cover SW (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
1435%424447%61%
1708
11th to 20thDay
3423323446%67%
1642
21st to endDay
36%3432335%6%63%
1782
February1st to 10thDay
15%24333346%66%
1620
11th to 20thDay
45%25%434345%62%
1735
21st to endDay
25%23322337%67%
1502
March1st to 10thDay
36%25%435%5%6%6%55%
1980
11th to 20thDay
45%24433346%62%
1980
21st to endDay
2424424447%63%
2186
April1st to 10thDay
241332345%8%64%
2160
11th to 20thDay
3424434446%63%
2131
21st to endDay
2323334446%66%
2160
May1st to 10thDay
222432445%6%66%
2160
11th to 20thDay
34345%36%6%6%6%55%
2205
21st to endDay
231332345%7%67%
2530
June1st to 10thDay
2323435%5%7%10%56%
2340
11th to 20thDay
232332345%6%67%
2340
21st to endDay
6%435%5%36%5%7%8%48%
2340
July1st to 10thDay
6%425%7%47%8%9%10%40%
2340
11th to 20thDay
4435%6%5%9%9%9%11%37%
2340
21st to endDay
4436%8%5%8%9%10%12%31%
2545
August1st to 10thDay
5%5%26%7%5%8%8%10%11%33%
2298
11th to 20thDay
5%335%7%47%7%8%12%38%
2123
21st to endDay
4425%6%46%8%9%10%42%
2376
September1st to 10thDay
7%5%25%5%35%6%7%7%47%
2160
11th to 20thDay
6%3245%45%6%6%7%52%
2160
21st to endDay
321432446%6%65%
1911
October1st to 10thDay
5%323434447%60%
1800
11th to 20thDay
431222323375%
1800
21st to endDay
221221233476%
1980
November1st to 10thDay
2312222348%72%
1859
11th to 20thDay
2213323436%72%
1862
21st to endDay
35%24423436%63%
1710
December1st to 10thDay
332432245%7%66%
1548
11th to 20thDay
36%245%345%5%6%58%
1930
21st to endDay
242332445%6%65%
3146
January1st to 10thNight
242433445%6%63%
2457
11th to 20thNight
3414424336%67%
2379
21st to endNight
2414334446%66%
2574
February1st to 10thNight
132442335%7%65%
2340
11th to 20thNight
35%25%424445%63%
2111
21st to endNight
2413324446%66%
1750
March1st to 10thNight
2423434447%64%
1980
11th to 20thNight
3424324346%66%
1980
21st to endNight
342332444468%
2170
April1st to 10thNight
231433445%7%64%
1800
11th to 20thNight
3424323336%68%
1777
21st to endNight
23245%2345%6%65%
1800
May1st to 10thNight
3324423346%66%
1800
11th to 20thNight
44235%35%5%5%6%59%
1685
21st to endNight
1313323346%70%
1746
June1st to 10thNight
25%24435%5%6%7%57%
1620
11th to 20thNight
3213435%346%66%
1620
21st to endNight
5%5%25%7%35%6%6%8%49%
1620
July1st to 10thNight
7%5%37%6%38%6%8%11%37%
1620
11th to 20thNight
4427%8%5%7%8%10%14%33%
1620
21st to endNight
45%36%7%47%8%9%13%34%
1773
August1st to 10thNight
34246%47%9%9%14%36%
1641
11th to 20thNight
5%5%35%6%5%7%8%8%11%38%
1778
21st to endNight
4425%5%35%8%9%11%43%
1980
September1st to 10thNight
6%5%246%47%6%5%8%46%
1800
11th to 20thNight
6%3244345%5%8%56%
1800
21st to endNight
5%31333345%5%65%
2044
October1st to 10thNight
5%42443345%6%61%
2160
11th to 20thNight
3212212235%75%
2160
21st to endNight
321231333474%
2376
November1st to 10thNight
2212213446%73%
2220
11th to 20thNight
1212213337%74%
2294
21st to endNight
35%34323445%65%
2470
December1st to 10thNight
342432345%7%63%
2629
11th to 20thNight
3325%5%35%5%6%8%55%
3271
21st to endNight
2423323445%66%
4544

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
21%5%6%18%37%13%
1709
11th to 20thDay
17%5%6%19%38%15%
1642
21st to endDay
21%35%17%34%19%
1782
February1st to 10thDay
19%46%17%29%25%
1620
11th to 20thDay
24%46%15%29%22%
1745
21st to endDay
16%4410%35%30%
1502
March1st to 10thDay
25%5%5%12%31%22%
1980
11th to 20thDay
22%5%5%12%32%24%
1980
21st to endDay
18%6%5%15%34%22%
2186
April1st to 10thDay
16%5%5%12%37%24%
2160
11th to 20thDay
20%4411%29%32%
2134
21st to endDay
17%5%5%14%35%24%
2160
May1st to 10thDay
18%45%11%33%29%
2160
11th to 20thDay
25%7%7%13%26%21%
2208
21st to endDay
15%5%7%11%27%35%
2530
June1st to 10thDay
19%6%7%16%24%28%
2340
11th to 20thDay
16%45%9%20%45%
2340
21st to endDay
27%7%10%14%18%23%
2340
July1st to 10thDay
30%11%13%14%17%14%
2276
11th to 20thDay
30%14%16%21%11%7%
2271
21st to endDay
34%15%21%21%7%2
2404
August1st to 10thDay
33%14%18%18%12%4
2283
11th to 20thDay
32%12%15%18%16%6%
2123
21st to endDay
29%13%14%20%19%5%
2376
September1st to 10thDay
31%9%9%19%19%13%
2160
11th to 20thDay
26%9%9%15%25%17%
2160
21st to endDay
17%6%7%18%31%21%
1911
October1st to 10thDay
23%6%8%16%23%25%
1800
11th to 20thDay
16%3310%31%38%
1800
21st to endDay
13%3417%41%22%
1980
November1st to 10thDay
12%4321%35%25%
1859
11th to 20thDay
14%4418%37%23%
1862
21st to endDay
22%5%415%34%21%
1710
December1st to 10thDay
18%5%6%24%32%16%
1548
11th to 20thDay
25%7%6%19%29%15%
1928
21st to endDay
16%7%7%18%29%23%
3146
January1st to 10thNight
20%5%7%18%36%15%
2457
11th to 20thNight
20%4418%40%14%
2379
21st to endNight
20%46%16%39%15%
2574
February1st to 10thNight
18%47%19%28%24%
2340
11th to 20thNight
22%5%420%25%24%
2111
21st to endNight
18%4313%33%28%
1750
March1st to 10thNight
20%45%15%33%23%
1980
11th to 20thNight
20%35%16%33%23%
1980
21st to endNight
18%46%18%32%21%
2170
April1st to 10thNight
18%45%13%35%25%
1800
11th to 20thNight
18%45%12%29%32%
1777
21st to endNight
18%5%5%13%37%22%
1800
May1st to 10thNight
19%45%9%31%31%
1800
11th to 20thNight
23%7%8%15%26%22%
1686
21st to endNight
16%35%12%26%37%
1746
June1st to 10thNight
22%7%8%14%20%30%
1620
11th to 20thNight
17%5%5%9%20%44%
1620
21st to endNight
29%7%11%13%14%26%
1620
July1st to 10thNight
37%9%12%18%15%10%
1575
11th to 20thNight
32%12%21%20%9%5%
1566
21st to endNight
34%14%23%20%8%1
1674
August1st to 10thNight
31%13%20%22%10%5%
1632
11th to 20thNight
34%11%17%17%14%7%
1778
21st to endNight
28%11%20%21%15%5%
1980
September1st to 10thNight
32%9%12%18%17%12%
1800
11th to 20thNight
24%6%10%17%21%22%
1800
21st to endNight
19%6%8%14%31%22%
2044
October1st to 10thNight
22%5%9%17%23%24%
2160
11th to 20thNight
14%3412%28%40%
2160
21st to endNight
14%4417%38%24%
2376
November1st to 10thNight
12%4420%36%25%
2220
11th to 20thNight
12%3419%34%28%
2294
21st to endNight
20%5%5%16%34%20%
2470
December1st to 10thNight
19%5%6%21%32%16%
2629
11th to 20thNight
24%7%7%18%30%15%
3272
21st to endNight
18%6%6%19%29%22%
4544

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
9%24%36%26%6%
270
11th to 20thDay
11%24%31%24%9%2
248
21st to endDay
6%29%36%18%11%
264
February1st to 10thDay
5%26%36%21%10%2
240
11th to 20thDay
13%25%42%18%3
240
21st to endDay
19%38%23%15%41
220
March1st to 10thDay
12%38%30%15%5%1
420
11th to 20thDay
14%30%32%16%6%1
420
21st to endDay
12%43%29%13%31
462
April1st to 10thDay
9%29%40%16%5%1
420
11th to 20thDay
14%33%34%13%5%
412
21st to endDay
11%32%35%17%4
420
May1st to 10thDay
7%27%42%20%4
423
11th to 20thDay
420%38%28%8%2
448
21st to endDay
5%22%42%23%7%1
485
June1st to 10thDay
413%33%36%13%1
450
11th to 20thDay
412%31%38%14%2
450
21st to endDay
7%7%27%39%18%3
450
July1st to 10thDay
5%316%37%33%6%
446
11th to 20thDay
5%111%34%39%11%
444
21st to endDay
418%36%37%14%
487
August1st to 10thDay
5%212%35%37%9%
447
11th to 20thDay
5%215%40%29%8%
437
21st to endDay
7%111%40%33%8%
495
September1st to 10thDay
9%317%39%26%6%
450
11th to 20thDay
5%423%43%21%3
450
21st to endDay
410%30%33%21%2
346
October1st to 10thDay
9%11%27%27%20%5%
270
11th to 20thDay
8%9%29%35%17%2
270
21st to endDay
8%16%25%31%17%3
297
November1st to 10thDay
7%19%34%29%10%1
270
11th to 20thDay
315%31%33%15%2
270
21st to endDay
5%31%29%23%11%1
270
December1st to 10thDay
6%23%37%27%7%
270
11th to 20thDay
432%31%23%9%
270
21st to endDay
12%28%33%21%5%
297
January1st to 10thNight
6%14%34%29%14%2
760
11th to 20thNight
5%20%35%25%13%3
732
21st to endNight
421%32%28%13%2
792
February1st to 10thNight
221%36%27%13%1
720
11th to 20thNight
6%21%39%25%8%1
704
21st to endNight
7%25%36%28%41
592
March1st to 10thNight
6%23%32%29%10%1
720
11th to 20thNight
6%18%32%30%12%1
720
21st to endNight
6%23%36%27%8%1
784
April1st to 10thNight
425%39%26%5%1
540
11th to 20thNight
6%29%34%25%7%
533
21st to endNight
324%41%23%8%
540
May1st to 10thNight
415%42%32%6%
540
11th to 20thNight
6%8%35%36%15%1
531
21st to endNight
39%41%37%10%1
584
June1st to 10thNight
47%31%40%16%1
540
11th to 20thNight
48%30%43%14%
540
21st to endNight
6%421%41%25%3
540
July1st to 10thNight
7%212%39%34%6%
525
11th to 20thNight
5%16%36%45%8%
522
21st to endNight
5%28%26%47%12%
591
August1st to 10thNight
326%27%51%11%
537
11th to 20thNight
5%29%35%43%5%
534
21st to endNight
427%34%45%8%
594
September1st to 10thNight
8%210%38%38%5%
540
11th to 20thNight
7%212%45%30%4
540
21st to endNight
4420%42%27%3
681
October1st to 10thNight
6%6%27%39%18%3
720
11th to 20thNight
5%6%31%39%18%2
720
21st to endNight
5%11%24%33%22%5%
792
November1st to 10thNight
49%24%39%21%3
740
11th to 20thNight
211%26%38%19%4
774
21st to endNight
6%19%24%31%18%2
950
December1st to 10thNight
5%15%31%34%13%1
950
11th to 20thNight
6%19%32%32%10%1
950
21st to endNight
5%21%32%33%8%1
846
Page generated at 2024-01-10 17:35:23. Version ac07

Copyright 2024 Attilla Danko


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