MAC-Hunter Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the MAC-Hunter 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
48%
24398
21%
74345
15%
24348
56%
24348
27%
46838

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
29%
758
23%
2459
10%
757
46%
757
26%
1498
January11th to 20thNight
35%
729
24%
2367
12%
729
49%
729
24%
1459
January21st to endNight
30%
792
27%
2574
15%
792
47%
792
27%
1560
February1st to 10thNight
35%
720
21%
2340
12%
720
47%
720
25%
1466
February11th to 20thNight
25%
701
20%
2144
10%
699
38%
699
23%
1401
February21st to endNight
29%
592
26%
1682
12%
592
42%
592
26%
1073
March1st to 10thNight
37%
720
26%
1980
15%
720
47%
720
31%
1238
March11th to 20thNight
34%
720
20%
1980
11%
720
42%
720
25%
1317
March21st to endNight
36%
792
21%
2178
8%
792
46%
792
29%
1403
April1st to 10thNight
37%
720
24%
1960
12%
720
46%
720
33%
1192
April11th to 20thNight
42%
711
25%
1775
12%
711
50%
711
37%
1113
April21st to endNight
49%
680
26%
1760
14%
680
54%
680
38%
1075
May1st to 10thNight
50%
540
21%
1620
12%
540
56%
540
33%
938
May11th to 20thNight
51%
531
15%
1592
8%
531
55%
531
24%
1065
May21st to endNight
64%
582
19%
1744
15%
582
66%
582
27%
1121
June1st to 10thNight
60%
540
15%
1620
13%
540
61%
540
24%
1114
June11th to 20thNight
62%
540
13%
1620
11%
540
64%
540
25%
1102
June21st to endNight
68%
540
14%
1620
12%
540
69%
540
25%
1100
July1st to 10thNight
66%
525
11%
1575
10%
525
66%
525
21%
1100
July11th to 20thNight
72%
522
10%
1566
9%
522
72%
522
24%
1066
July21st to endNight
69%
591
14%
1672
12%
558
70%
558
25%
1127
August1st to 10thNight
68%
537
13%
1600
11%
534
69%
534
22%
1131
August11th to 20thNight
65%
534
13%
1598
12%
534
65%
534
21%
1128
August21st to endNight
63%
783
14%
1971
10%
783
63%
783
25%
1425
September1st to 10thNight
67%
720
19%
1903
15%
720
68%
720
30%
1262
September11th to 20thNight
61%
720
19%
1980
16%
720
63%
720
26%
1331
September21st to endNight
54%
720
19%
1980
15%
720
58%
720
25%
1361
October1st to 10thNight
57%
720
24%
2117
22%
720
62%
720
34%
1265
October11th to 20thNight
54%
720
31%
2160
27%
720
63%
720
35%
1229
October21st to endNight
52%
792
31%
2376
24%
792
63%
792
36%
1327
November1st to 10thNight
51%
740
28%
2221
23%
740
60%
740
35%
1275
November11th to 20thNight
44%
760
30%
2338
22%
760
55%
760
32%
1366
November21st to endNight
45%
760
26%
2470
20%
760
56%
760
30%
1435
December1st to 10thNight
37%
760
24%
2470
15%
760
49%
760
22%
1583
December11th to 20thNight
41%
759
28%
2929
21%
758
51%
758
25%
1669
December21st to endNight
37%
827
17%
4404
16%
817
47%
817
14%
2523

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
13%5%25%5%35%5%6%8%44%
74942
Night
13%5%25%5%345%5%7%45%
74795
TransparencyDay
38%8%12%20%18%5%
74665
Night
38%7%11%18%19%6%
74591
SeeingDay
14%6%22%24%21%11%
14273
Night
15%6%23%33%21%2
24414

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
15%6%36%424446%46%
1706
11th to 20thDay
15%6%25%5%345%45%46%
1638
21st to endDay
16%6%34433445%47%
1782
February1st to 10thDay
16%8%35%5%2445%6%43%
1620
11th to 20thDay
20%5%25%324445%46%
1699
21st to endDay
20%6%26%5%34445%42%
1573
March1st to 10thDay
15%5%24423345%52%
1980
11th to 20thDay
16%6%35%5%2446%7%42%
1980
21st to endDay
14%6%36%5%3445%7%42%
2178
April1st to 10thDay
10%424326%5%6%9%51%
1998
11th to 20thDay
11%5%24435%45%8%48%
2134
21st to endDay
10%5%244245%5%7%52%
2214
May1st to 10thDay
7%5%246%45%6%5%9%47%
2340
11th to 20thDay
12%6%36%6%35%5%6%8%40%
2301
21st to endDay
11%5%26%6%46%5%7%9%39%
2531
June1st to 10thDay
9%6%26%7%36%6%8%11%37%
2340
11th to 20thDay
8%4245%46%7%9%12%39%
2340
21st to endDay
7%427%6%46%6%7%12%40%
2340
July1st to 10thDay
8%5%26%7%47%7%8%11%36%
2340
11th to 20thDay
9%6%26%6%47%8%7%11%34%
2340
21st to endDay
6%5%25%6%47%8%9%12%35%
2547
August1st to 10thDay
12%435%7%46%7%10%11%31%
2327
11th to 20thDay
13%7%36%7%47%6%6%10%31%
2292
21st to endDay
11%6%26%6%46%7%8%10%34%
2376
September1st to 10thDay
8%426%6%46%6%6%9%44%
2052
11th to 20thDay
12%6%25%5%45%5%5%8%43%
1980
21st to endDay
17%6%26%5%3345%6%42%
1980
October1st to 10thDay
15%6%24423446%50%
1841
11th to 20thDay
11%41443435%6%56%
1800
21st to endDay
12%413333345%57%
1980
November1st to 10thDay
13%423333345%57%
1857
11th to 20thDay
15%5%24323346%53%
1839
21st to endDay
14%5%245%2335%6%50%
1710
December1st to 10thDay
18%7%36%5%335%5%7%39%
1710
11th to 20thDay
16%424323346%54%
2153
21st to endDay
18%7%34323446%45%
3124
January1st to 10thNight
17%5%35%433345%47%
2459
11th to 20thNight
14%5%345%345%5%6%45%
2367
21st to endNight
17%6%25%434445%47%
2574
February1st to 10thNight
18%5%25%425%5%47%43%
2340
11th to 20thNight
19%6%25%5%34345%44%
2144
21st to endNight
15%6%25%5%33446%46%
1682
March1st to 10thNight
15%5%34424446%49%
1980
11th to 20thNight
16%5%26%5%445%5%7%42%
1980
21st to endNight
14%425%5%35%46%8%44%
2178
April1st to 10thNight
12%5%2443446%6%52%
1960
11th to 20thNight
11%5%25%424446%53%
1775
21st to endNight
11%42443446%8%52%
1760
May1st to 10thNight
9%5%245%345%7%8%49%
1620
11th to 20thNight
12%6%35%6%5%5%5%7%9%37%
1592
21st to endNight
10%5%25%6%35%6%6%9%42%
1744
June1st to 10thNight
11%5%36%5%46%8%7%8%36%
1620
11th to 20thNight
10%6%35%6%47%6%8%11%35%
1620
21st to endNight
8%436%5%36%8%8%12%37%
1620
July1st to 10thNight
7%5%27%8%47%7%8%12%32%
1620
11th to 20thNight
8%425%7%47%7%8%12%35%
1620
21st to endNight
7%5%36%7%47%7%9%11%35%
1771
August1st to 10thNight
10%5%36%7%5%6%6%10%11%32%
1611
11th to 20thNight
11%5%37%7%47%6%8%11%32%
1598
21st to endNight
10%6%37%7%46%6%7%12%31%
1971
September1st to 10thNight
8%5%25%6%35%6%7%10%42%
1903
11th to 20thNight
12%7%35%6%35%45%7%41%
1980
21st to endNight
16%6%36%5%35%5%45%42%
1980
October1st to 10thNight
14%6%24324346%53%
2117
11th to 20thNight
14%424333346%54%
2160
21st to endNight
10%5%24333445%57%
2376
November1st to 10thNight
12%5%34323335%56%
2221
11th to 20thNight
13%6%24324345%54%
2338
21st to endNight
15%425%42346%6%49%
2470
December1st to 10thNight
18%7%35%5%24346%43%
2470
11th to 20thNight
17%5%24422335%52%
3042
21st to endNight
19%6%2443445%6%42%
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
40%5%8%19%22%6%
1707
11th to 20thDay
41%6%8%17%22%6%
1638
21st to endDay
39%35%20%24%8%
1782
February1st to 10thDay
43%49%20%19%5%
1620
11th to 20thDay
42%5%5%19%24%6%
1709
21st to endDay
44%5%8%15%19%8%
1573
March1st to 10thDay
35%47%21%24%9%
1980
11th to 20thDay
43%6%9%19%17%7%
1980
21st to endDay
42%6%10%20%19%4
2178
April1st to 10thDay
30%6%11%20%27%6%
1998
11th to 20thDay
34%6%10%20%19%11%
2134
21st to endDay
32%6%12%25%22%4
2214
May1st to 10thDay
33%8%14%22%20%3
2340
11th to 20thDay
40%7%15%20%16%1
2305
21st to endDay
39%10%13%21%16%1
2531
June1st to 10thDay
38%11%17%23%10%2
2340
11th to 20thDay
33%11%20%22%13%1
2340
21st to endDay
34%12%18%22%12%2
2340
July1st to 10thDay
37%14%19%17%10%3
2275
11th to 20thDay
38%13%24%17%7%1
2271
21st to endDay
36%14%21%21%8%1
2405
August1st to 10thDay
41%13%18%18%8%1
2314
11th to 20thDay
45%12%18%16%9%
2292
21st to endDay
41%12%17%18%9%2
2376
September1st to 10thDay
36%9%16%18%18%4
2052
11th to 20thDay
39%8%11%16%22%4
1980
21st to endDay
43%6%9%21%16%6%
1980
October1st to 10thDay
36%5%8%19%26%5%
1841
11th to 20thDay
30%6%7%25%24%8%
1800
21st to endDay
30%47%19%28%12%
1980
November1st to 10thDay
31%45%19%28%12%
1857
11th to 20thDay
34%47%19%26%10%
1839
21st to endDay
36%48%20%23%9%
1710
December1st to 10thDay
45%5%8%19%18%5%
1710
11th to 20thDay
34%38%22%25%9%
2150
21st to endDay
41%5%7%21%23%3
3124
January1st to 10thNight
39%49%17%24%7%
2459
11th to 20thNight
40%5%9%17%22%7%
2367
21st to endNight
40%35%19%24%9%
2574
February1st to 10thNight
41%5%8%18%20%8%
2340
11th to 20thNight
43%5%7%16%22%7%
2145
21st to endNight
40%5%10%17%19%10%
1682
March1st to 10thNight
37%5%8%17%22%11%
1980
11th to 20thNight
42%6%10%16%20%7%
1980
21st to endNight
38%6%12%19%19%6%
2178
April1st to 10thNight
33%5%10%20%24%9%
1960
11th to 20thNight
32%5%9%22%21%11%
1775
21st to endNight
31%6%12%24%23%5%
1760
May1st to 10thNight
31%7%16%23%19%5%
1620
11th to 20thNight
41%9%14%18%17%1
1593
21st to endNight
37%10%13%25%13%3
1745
June1st to 10thNight
41%11%14%22%10%1
1620
11th to 20thNight
38%12%18%18%11%2
1620
21st to endNight
36%15%17%19%10%3
1620
July1st to 10thNight
41%14%20%14%9%3
1575
11th to 20thNight
36%15%24%15%7%2
1566
21st to endNight
37%13%22%18%10%1
1672
August1st to 10thNight
41%14%19%21%5%1
1600
11th to 20thNight
43%12%21%15%8%1
1598
21st to endNight
43%11%19%18%7%2
1971
September1st to 10thNight
36%10%16%19%13%6%
1903
11th to 20thNight
41%8%13%16%19%4
1980
21st to endNight
44%7%11%18%16%5%
1980
October1st to 10thNight
33%6%10%19%26%6%
2117
11th to 20thNight
32%48%22%24%10%
2160
21st to endNight
29%5%7%19%27%13%
2376
November1st to 10thNight
32%48%14%28%14%
2221
11th to 20thNight
34%46%17%26%12%
2338
21st to endNight
35%5%8%20%24%9%
2470
December1st to 10thNight
43%5%9%16%19%6%
2470
11th to 20thNight
37%46%19%25%10%
3044
21st to endNight
42%5%7%19%23%4
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
18%11%46%19%6%
270
11th to 20thDay
14%12%41%25%8%
246
21st to endDay
23%17%35%20%6%
264
February1st to 10thDay
19%15%37%21%8%
240
11th to 20thDay
31%10%39%16%3
240
21st to endDay
21%16%38%20%41
291
March1st to 10thDay
18%11%36%26%9%
420
11th to 20thDay
18%14%38%23%7%1
420
21st to endDay
16%13%34%26%10%2
462
April1st to 10thDay
15%14%31%24%15%1
420
11th to 20thDay
9%9%32%25%17%7%
412
21st to endDay
13%7%26%26%20%7%
420
May1st to 10thDay
7%10%33%24%19%6%
423
11th to 20thDay
16%317%25%26%14%
447
21st to endDay
15%212%24%27%20%
485
June1st to 10thDay
11%311%31%28%17%
450
11th to 20thDay
10%215%26%26%22%
450
21st to endDay
9%210%29%30%20%
450
July1st to 10thDay
9%15%23%30%31%
445
11th to 20thDay
10%26%19%35%27%
444
21st to endDay
6%28%23%39%22%
488
August1st to 10thDay
14%19%23%28%24%
446
11th to 20thDay
13%25%21%34%25%
439
21st to endDay
12%211%19%32%24%
495
September1st to 10thDay
9%28%25%36%20%
450
11th to 20thDay
15%113%23%32%16%
450
21st to endDay
19%215%27%25%12%
450
October1st to 10thDay
17%318%27%23%12%
450
11th to 20thDay
11%5%24%26%24%10%
450
21st to endDay
13%5%24%27%24%7%
495
November1st to 10thDay
17%426%29%18%6%
455
11th to 20thDay
21%6%32%27%12%2
399
21st to endDay
12%8%34%28%16%3
270
December1st to 10thDay
21%14%34%22%9%1
270
11th to 20thDay
23%5%35%24%12%1
270
21st to endDay
22%11%38%15%10%3
297
January1st to 10thNight
20%9%37%27%8%
760
11th to 20thNight
17%10%34%31%8%
729
21st to endNight
20%6%38%32%3
792
February1st to 10thNight
20%10%33%32%6%
720
11th to 20thNight
21%12%38%27%2
703
21st to endNight
17%13%38%28%5%
592
March1st to 10thNight
17%8%34%35%6%
720
11th to 20thNight
17%10%34%29%9%1
720
21st to endNight
16%8%35%33%8%
792
April1st to 10thNight
14%12%34%30%10%
720
11th to 20thNight
12%10%31%31%16%
711
21st to endNight
12%6%28%41%13%
680
May1st to 10thNight
12%6%27%41%14%
540
11th to 20thNight
13%5%22%40%18%2
531
21st to endNight
10%213%34%38%3
584
June1st to 10thNight
11%412%40%30%3
540
11th to 20thNight
10%214%34%32%8%
540
21st to endNight
8%210%41%31%8%
540
July1st to 10thNight
8%27%34%42%6%
525
11th to 20thNight
10%16%29%48%7%
522
21st to endNight
7%27%35%45%5%
591
August1st to 10thNight
13%26%26%45%8%
537
11th to 20thNight
13%26%31%41%7%
534
21st to endNight
12%28%29%43%6%
783
September1st to 10thNight
8%29%30%44%7%
720
11th to 20thNight
15%310%29%38%5%
720
21st to endNight
20%213%32%30%2
720
October1st to 10thNight
16%318%30%28%5%
720
11th to 20thNight
16%422%32%25%2
720
21st to endNight
12%7%23%34%22%2
792
November1st to 10thNight
15%424%33%19%4
740
11th to 20thNight
16%8%27%35%12%1
760
21st to endNight
16%7%28%33%16%1
760
December1st to 10thNight
20%8%30%34%8%1
760
11th to 20thNight
18%6%29%35%11%1
760
21st to endNight
23%9%27%33%9%
836
Page generated at 2024-01-10 01:24:58. Version ac07

Copyright 2024 Attilla Danko


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