Milagro Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Milagro Observatory clear sky chart from 2005-11-06 to 2024-03-08.

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
60%
24439
28%
79975
22%
24346
67%
24346
37%
42734

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
59%
751
28%
4019
26%
736
67%
736
24%
2043
January11th to 20thNight
56%
755
29%
4034
29%
740
64%
740
26%
1885
January21st to endNight
50%
828
22%
4305
25%
814
62%
814
22%
2319
February1st to 10thNight
51%
760
28%
2470
21%
760
63%
760
39%
1298
February11th to 20thNight
48%
741
27%
2403
20%
740
58%
740
35%
1295
February21st to endNight
45%
628
31%
1804
21%
628
55%
628
36%
1052
March1st to 10thNight
49%
750
28%
2062
18%
750
57%
750
36%
1233
March11th to 20thNight
55%
720
30%
1980
20%
720
61%
720
39%
1162
March21st to endNight
48%
792
25%
2178
15%
792
55%
792
32%
1349
April1st to 10thNight
48%
586
26%
1846
16%
586
61%
586
32%
1034
April11th to 20thNight
45%
533
28%
1777
19%
533
57%
533
30%
956
April21st to endNight
47%
540
31%
1794
20%
540
62%
540
36%
914
May1st to 10thNight
54%
540
30%
1620
21%
540
63%
540
39%
879
May11th to 20thNight
58%
531
27%
1595
21%
531
64%
531
39%
861
May21st to endNight
56%
583
27%
1702
19%
582
62%
582
40%
906
June1st to 10thNight
72%
540
34%
1440
25%
540
77%
540
58%
719
June11th to 20thNight
69%
540
35%
1440
27%
540
74%
540
58%
710
June21st to endNight
75%
540
30%
1475
25%
540
79%
540
57%
740
July1st to 10thNight
73%
525
20%
1575
17%
525
75%
525
38%
876
July11th to 20thNight
78%
522
19%
1566
17%
522
78%
522
33%
950
July21st to endNight
72%
591
17%
1674
14%
558
73%
558
26%
1085
August1st to 10thNight
78%
537
21%
1602
19%
534
78%
534
34%
944
August11th to 20thNight
77%
534
28%
1628
26%
534
78%
534
37%
911
August21st to endNight
79%
594
27%
1980
30%
594
80%
594
37%
1050
September1st to 10thNight
73%
540
29%
1800
31%
540
76%
540
35%
979
September11th to 20thNight
74%
634
35%
1894
32%
634
77%
634
46%
995
September21st to endNight
71%
720
36%
2014
25%
720
77%
720
53%
1009
October1st to 10thNight
61%
720
29%
2160
20%
720
67%
720
42%
1144
October11th to 20thNight
71%
720
38%
2160
27%
720
80%
720
58%
993
October21st to endNight
63%
792
40%
2376
27%
792
73%
792
51%
1147
November1st to 10thNight
67%
740
38%
2220
28%
740
74%
740
52%
1060
November11th to 20thNight
67%
817
39%
2397
29%
817
74%
817
54%
1143
November21st to endNight
58%
950
31%
2660
21%
950
65%
950
45%
1425
December1st to 10thNight
59%
950
28%
2660
20%
950
64%
950
41%
1508
December11th to 20thNight
52%
948
25%
3135
17%
948
57%
948
28%
1914
December21st to endNight
47%
947
15%
4530
17%
936
54%
936
23%
2246

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
45%244345%5%7%57%
78728
Night
5%6%2443445%6%57%
80887
TransparencyDay
26%5%9%20%25%15%
78453
Night
27%5%8%20%24%15%
80683
SeeingDay
7%13%26%31%19%4
14063
Night
8%6%20%39%24%4
24475

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
47%25%43446%6%55%
2858
11th to 20thDay
47%25%7%45%446%52%
2860
21st to endDay
6%11%34424345%54%
3146
February1st to 10thDay
49%35%5%3435%6%54%
1710
11th to 20thDay
5%8%36%6%3445%6%50%
1665
21st to endDay
6%11%35%6%34445%49%
1645
March1st to 10thDay
7%8%345%445%5%7%48%
2058
11th to 20thDay
47%36%5%346%6%7%50%
1980
21st to endDay
6%7%36%5%345%5%7%50%
2178
April1st to 10thDay
5%5%25%5%35%45%6%56%
2112
11th to 20thDay
35%25%436%6%47%54%
2131
21st to endDay
4424435%5%7%7%55%
2163
May1st to 10thDay
4424435%5%6%8%54%
2340
11th to 20thDay
45%234445%6%8%54%
2301
21st to endDay
432442445%6%63%
2569
June1st to 10thDay
321232345%8%67%
2520
11th to 20thDay
3212322245%74%
2520
21st to endDay
11133245%5%6%69%
2478
July1st to 10thDay
32235%35%6%7%9%56%
2340
11th to 20thDay
23245%45%7%8%11%51%
2340
21st to endDay
6%425%6%47%7%8%11%40%
2545
August1st to 10thDay
5%416%6%45%7%8%8%47%
2328
11th to 20thDay
33145%46%6%6%9%53%
2271
21st to endDay
33145%45%6%8%9%52%
2376
September1st to 10thDay
6%3245%345%6%7%56%
2160
11th to 20thDay
43134345%6%6%59%
2063
21st to endDay
4313322335%71%
1944
October1st to 10thDay
7%424433348%59%
1800
11th to 20thDay
421222234474%
1800
21st to endDay
3413423336%69%
1980
November1st to 10thDay
3312332348%68%
1859
11th to 20thDay
431332235%5%69%
1759
21st to endDay
5%6%3442334462%
1520
December1st to 10thDay
7%8%24424446%55%
1520
11th to 20thDay
8%7%35%5%346%6%6%46%
1926
21st to endDay
6%9%36%424446%53%
2963
January1st to 10thNight
47%37%6%3445%5%52%
4097
11th to 20thNight
48%34434347%56%
4110
21st to endNight
6%10%36%433446%50%
4521
February1st to 10thNight
48%35%423345%59%
2470
11th to 20thNight
7%6%35%43445%6%55%
2402
21st to endNight
6%9%35%434446%52%
1804
March1st to 10thNight
6%6%36%44445%6%52%
2062
11th to 20thNight
48%245%35%446%55%
1980
21st to endNight
7%7%35%5%346%5%6%49%
2178
April1st to 10thNight
7%6%244446%5%6%51%
1846
11th to 20thNight
6%5%25%435%446%56%
1777
21st to endNight
44245%35%45%5%61%
1794
May1st to 10thNight
5%425%5%3335%8%57%
1620
11th to 20thNight
6%5%25%423347%59%
1594
21st to endNight
6%32442445%6%60%
1702
June1st to 10thNight
221232336%7%68%
1440
11th to 20thNight
3213312345%71%
1440
21st to endNight
12133245%5%7%65%
1475
July1st to 10thNight
3325%5%46%6%7%9%52%
1620
11th to 20thNight
2225%7%5%7%7%7%8%46%
1620
21st to endNight
4427%7%48%8%9%13%34%
1773
August1st to 10thNight
2325%6%36%7%7%10%48%
1611
11th to 20thNight
44245%35%5%7%10%50%
1628
21st to endNight
3325%5%35%7%7%10%51%
1980
September1st to 10thNight
5%3245%46%5%7%7%52%
1800
11th to 20thNight
4324423447%62%
1894
21st to endNight
5%313423335%69%
2014
October1st to 10thNight
7%41432345%6%61%
2160
11th to 20thNight
221231333474%
2160
21st to endNight
4324322335%69%
2376
November1st to 10thNight
5%413212446%68%
2220
11th to 20thNight
4313213345%70%
2397
21st to endNight
6%6%24323345%62%
2660
December1st to 10thNight
7%7%24424345%59%
2660
11th to 20thNight
7%8%36%6%3435%7%48%
3271
21st to endNight
6%10%35%423336%55%
4731

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
29%5%15%31%18%2
2859
11th to 20thDay
33%418%30%13%2
2860
21st to endDay
34%49%28%20%4
3146
February1st to 10thDay
32%414%22%21%6%
1710
11th to 20thDay
36%49%23%23%6%
1674
21st to endDay
37%37%16%30%6%
1645
March1st to 10thDay
34%5%7%21%26%7%
2058
11th to 20thDay
31%5%8%24%25%6%
1980
21st to endDay
34%48%20%27%6%
2178
April1st to 10thDay
29%47%19%27%15%
2112
11th to 20thDay
28%5%6%18%26%15%
2134
21st to endDay
24%5%7%21%30%13%
2163
May1st to 10thDay
27%5%8%16%31%13%
2340
11th to 20thDay
25%6%10%18%30%12%
2304
21st to endDay
21%47%15%29%24%
2569
June1st to 10thDay
15%36%15%31%29%
2520
11th to 20thDay
14%348%22%48%
2520
21st to endDay
13%45%12%25%41%
2478
July1st to 10thDay
21%7%11%13%19%29%
2276
11th to 20thDay
23%8%14%20%18%17%
2271
21st to endDay
31%11%17%18%14%8%
2404
August1st to 10thDay
30%10%12%15%14%19%
2313
11th to 20thDay
24%7%11%17%18%22%
2271
21st to endDay
24%7%10%19%25%16%
2376
September1st to 10thDay
26%5%9%13%23%25%
2160
11th to 20thDay
22%6%10%15%21%26%
2063
21st to endDay
18%35%14%36%24%
1944
October1st to 10thDay
26%5%8%18%27%17%
1800
11th to 20thDay
14%3317%40%23%
1800
21st to endDay
19%37%22%38%10%
1980
November1st to 10thDay
18%27%26%37%10%
1859
11th to 20thDay
18%37%29%36%7%
1759
21st to endDay
27%48%24%28%9%
1520
December1st to 10thDay
31%5%12%28%19%6%
1520
11th to 20thDay
37%6%12%25%19%1
1924
21st to endDay
33%5%11%16%24%10%
2963
January1st to 10thNight
32%5%10%32%18%2
4097
11th to 20thNight
29%416%31%16%3
4110
21st to endNight
35%48%29%21%3
4521
February1st to 10thNight
28%312%25%24%8%
2470
11th to 20thNight
30%49%23%28%7%
2403
21st to endNight
33%37%19%29%9%
1804
March1st to 10thNight
31%5%6%22%28%8%
2062
11th to 20thNight
30%5%6%23%28%8%
1980
21st to endNight
35%48%20%25%7%
2178
April1st to 10thNight
31%46%18%26%14%
1846
11th to 20thNight
29%5%6%15%29%17%
1777
21st to endNight
26%45%19%32%14%
1794
May1st to 10thNight
27%5%6%14%35%14%
1620
11th to 20thNight
26%6%7%20%26%15%
1595
21st to endNight
25%5%8%14%24%24%
1702
June1st to 10thNight
16%45%14%28%34%
1440
11th to 20thNight
16%4410%20%47%
1440
21st to endNight
16%5%6%11%21%41%
1475
July1st to 10thNight
25%9%12%11%13%30%
1575
11th to 20thNight
31%10%12%12%16%20%
1566
21st to endNight
37%11%15%18%9%10%
1674
August1st to 10thNight
28%11%12%15%15%20%
1602
11th to 20thNight
27%8%11%15%14%25%
1628
21st to endNight
25%8%12%17%21%18%
1980
September1st to 10thNight
28%7%8%14%16%27%
1800
11th to 20thNight
24%47%17%19%28%
1894
21st to endNight
19%35%12%31%29%
2014
October1st to 10thNight
25%5%8%17%21%25%
2160
11th to 20thNight
15%35%12%36%27%
2160
21st to endNight
19%3422%36%16%
2376
November1st to 10thNight
20%25%21%36%15%
2220
11th to 20thNight
18%27%25%38%9%
2397
21st to endNight
26%27%21%32%12%
2660
December1st to 10thNight
29%310%28%21%9%
2660
11th to 20thNight
36%5%9%24%24%3
3272
21st to endNight
32%410%19%24%12%
4731

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
16%11%28%27%15%2
270
11th to 20thDay
12%13%33%27%14%1
270
21st to endDay
9%9%32%32%15%3
297
February1st to 10thDay
9%16%30%33%11%1
270
11th to 20thDay
11%18%33%28%10%
270
21st to endDay
11%22%37%22%8%
306
March1st to 10thDay
12%22%35%22%9%
449
11th to 20thDay
10%20%32%25%11%1
420
21st to endDay
12%30%35%17%5%1
462
April1st to 10thDay
8%21%36%22%10%2
420
11th to 20thDay
11%28%36%16%8%2
412
21st to endDay
9%27%34%20%9%
420
May1st to 10thDay
9%20%35%26%8%1
423
11th to 20thDay
7%16%30%29%15%3
448
21st to endDay
9%18%28%25%15%4
524
June1st to 10thDay
37%23%37%24%5%
630
11th to 20thDay
39%24%35%22%6%
630
21st to endDay
16%24%42%22%4
588
July1st to 10thDay
2313%45%31%5%
446
11th to 20thDay
329%38%36%13%
444
21st to endDay
6%111%38%34%10%
487
August1st to 10thDay
5%313%44%28%6%
447
11th to 20thDay
3418%40%27%9%
437
21st to endDay
4217%37%32%7%
495
September1st to 10thDay
7%217%38%27%8%
450
11th to 20thDay
46%24%36%24%6%
450
21st to endDay
412%21%32%22%8%
414
October1st to 10thDay
9%14%24%19%23%11%
270
11th to 20thDay
5%13%24%30%21%6%
270
21st to endDay
7%18%20%32%19%4
297
November1st to 10thDay
7%16%26%29%19%4
270
11th to 20thDay
413%30%31%17%4
270
21st to endDay
9%13%27%29%17%4
270
December1st to 10thDay
10%11%26%33%16%3
270
11th to 20thDay
10%11%30%27%18%4
270
21st to endDay
18%13%27%30%13%
297
January1st to 10thNight
9%421%41%20%4
760
11th to 20thNight
10%5%24%39%21%3
760
21st to endNight
10%6%26%37%17%4
836
February1st to 10thNight
8%6%30%39%15%2
760
11th to 20thNight
9%8%29%40%13%1
744
21st to endNight
13%8%29%37%12%1
628
March1st to 10thNight
10%8%28%36%16%2
750
11th to 20thNight
7%8%24%38%21%2
720
21st to endNight
9%12%24%38%15%2
792
April1st to 10thNight
11%11%25%41%10%1
586
11th to 20thNight
10%16%24%33%15%2
533
21st to endNight
7%13%29%38%13%2
540
May1st to 10thNight
8%9%24%41%16%1
540
11th to 20thNight
9%424%40%20%4
531
21st to endNight
7%10%22%35%22%3
584
June1st to 10thNight
2418%43%31%2
540
11th to 20thNight
4419%41%28%3
540
21st to endNight
2216%42%34%4
540
July1st to 10thNight
5%111%37%42%4
525
11th to 20thNight
317%34%49%7%
522
21st to endNight
5%17%29%49%8%
591
August1st to 10thNight
317%33%47%10%
537
11th to 20thNight
5%26%38%41%6%
534
21st to endNight
417%37%44%7%
594
September1st to 10thNight
5%111%42%36%5%
540
11th to 20thNight
4214%40%34%6%
634
21st to endNight
7%414%37%31%7%
720
October1st to 10thNight
9%5%22%38%24%3
720
11th to 20thNight
4318%48%23%4
720
21st to endNight
6%7%20%37%25%5%
792
November1st to 10thNight
7%418%43%24%5%
740
11th to 20thNight
5%6%19%44%22%5%
817
21st to endNight
10%9%20%35%21%5%
950
December1st to 10thNight
11%5%20%44%18%2
950
11th to 20thNight
14%6%22%38%19%2
950
21st to endNight
13%9%21%40%14%2
955
Page generated at 2024-03-05 05:24:01. Version ac07

Copyright © 2024 Attilla Danko.


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