Two Goats Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Two Goats Observatory clear sky chart from 2005-11-06 to 2024-01-15.

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
66%
24256
36%
74434
28%
24197
75%
24197
57%
33678

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
51%
760
28%
2646
22%
756
63%
756
37%
1316
January11th to 20thNight
51%
736
36%
2445
25%
736
68%
736
47%
1142
January21st to endNight
47%
792
37%
2416
24%
792
64%
792
41%
1235
February1st to 10thNight
52%
720
36%
2160
25%
720
67%
720
46%
1081
February11th to 20thNight
52%
700
35%
2098
25%
700
68%
700
49%
1032
February21st to endNight
49%
592
31%
1776
23%
592
62%
592
47%
884
March1st to 10thNight
49%
720
27%
2160
21%
720
60%
720
43%
1107
March11th to 20thNight
58%
720
27%
2102
22%
720
66%
720
48%
1069
March21st to endNight
53%
792
32%
1980
17%
792
63%
792
54%
1070
April1st to 10thNight
53%
720
34%
1800
16%
720
63%
720
55%
969
April11th to 20thNight
53%
711
37%
1779
16%
711
62%
711
66%
872
April21st to endNight
59%
720
35%
1800
16%
720
66%
720
68%
863
May1st to 10thNight
58%
656
33%
1736
18%
656
64%
656
70%
793
May11th to 20thNight
63%
531
40%
1595
26%
531
71%
531
70%
647
May21st to endNight
58%
582
36%
1746
21%
582
68%
582
71%
690
June1st to 10thNight
72%
454
36%
1534
31%
454
78%
454
72%
558
June11th to 20thNight
81%
360
43%
1440
44%
360
90%
360
82%
411
June21st to endNight
85%
360
43%
1440
47%
360
90%
360
80%
417
July1st to 10thNight
94%
350
41%
1400
49%
350
94%
350
76%
426
July11th to 20thNight
92%
348
41%
1392
48%
348
92%
348
66%
462
July21st to endNight
89%
712
38%
1789
28%
673
90%
673
73%
812
August1st to 10thNight
88%
716
37%
1780
24%
712
89%
712
80%
801
August11th to 20thNight
93%
712
43%
1780
26%
712
93%
712
86%
774
August21st to endNight
93%
792
46%
1980
31%
792
93%
792
84%
868
September1st to 10thNight
88%
720
46%
1800
35%
720
89%
720
83%
803
September11th to 20thNight
88%
720
49%
1921
40%
720
92%
720
87%
781
September21st to endNight
80%
720
47%
1980
39%
720
89%
720
84%
802
October1st to 10thNight
74%
720
41%
1980
32%
720
84%
720
69%
885
October11th to 20thNight
73%
720
44%
2114
39%
720
82%
720
70%
876
October21st to endNight
67%
792
44%
2414
38%
792
79%
792
65%
1012
November1st to 10thNight
70%
740
38%
2405
35%
740
80%
740
62%
977
November11th to 20thNight
68%
760
39%
2470
33%
760
81%
760
60%
1025
November21st to endNight
61%
760
36%
2470
33%
760
71%
760
49%
1147
December1st to 10thNight
52%
760
34%
2470
25%
760
66%
760
44%
1200
December11th to 20thNight
53%
760
29%
2972
25%
759
66%
759
29%
1663
December21st to endNight
48%
828
20%
4664
23%
817
63%
817
24%
2208

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
2212323346%72%
74936
Night
221332345%7%69%
74850
TransparencyDay
14%37%16%28%32%
74658
Night
14%48%17%28%29%
74649
SeeingDay
312%28%33%18%5%
14381
Night
35%23%40%25%4
24270

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
44243345%5%9%57%
1519
11th to 20thDay
5%324324348%63%
1600
21st to endDay
6%5%25%423348%58%
1936
February1st to 10thDay
3424334446%64%
1800
11th to 20thDay
332332335%8%65%
1750
21st to endDay
33344345%5%6%60%
1480
March1st to 10thDay
34247%45%5%7%9%53%
1800
11th to 20thDay
3413425%5%6%10%57%
1852
21st to endDay
2223325%6%6%8%61%
2376
April1st to 10thDay
3323324447%66%
2160
11th to 20thDay
1212323336%74%
2129
21st to endDay
1112223349%72%
2160
May1st to 10thDay
111222345%8%71%
2222
11th to 20thDay
1112212337%76%
2301
21st to endDay
1112322346%75%
2530
June1st to 10thDay
112222237%78%
2420
11th to 20thDay
1111225%87%
2520
21st to endDay
11121112287%
2520
July1st to 10thDay
11121223483%
2520
11th to 20thDay
211221223481%
2520
21st to endDay
2212212347%76%
2417
August1st to 10thDay
111221223383%
2149
11th to 20thDay
1111113487%
2122
21st to endDay
1121223484%
2376
September1st to 10thDay
111111123384%
2160
11th to 20thDay
1111113487%
2039
21st to endDay
1212235%83%
1980
October1st to 10thDay
2112222245%77%
1980
11th to 20thDay
11222233481%
1841
21st to endDay
1112213345%78%
1940
November1st to 10thDay
1112323346%74%
1674
11th to 20thDay
131332335%6%70%
1710
21st to endDay
232343445%9%62%
1710
December1st to 10thDay
33244345%5%7%59%
1710
11th to 20thDay
5%6%25%6%45%6%5%8%47%
2169
21st to endDay
7%7%26%7%446%5%7%46%
2844
January1st to 10thNight
442443446%8%56%
2646
11th to 20thNight
331442445%9%62%
2445
21st to endNight
442443435%6%60%
2416
February1st to 10thNight
242442345%6%64%
2160
11th to 20thNight
3324423447%65%
2098
21st to endNight
3214435%46%7%60%
1776
March1st to 10thNight
2324436%6%7%10%53%
2160
11th to 20thNight
23234345%7%9%59%
2102
21st to endNight
32144245%5%8%62%
1980
April1st to 10thNight
232342345%7%66%
1800
11th to 20thNight
111231335%7%72%
1779
21st to endNight
221121335%9%71%
1800
May1st to 10thNight
122447%9%69%
1736
11th to 20thNight
12212348%77%
1594
21st to endNight
1111112348%77%
1746
June1st to 10thNight
11212448%78%
1534
11th to 20thNight
111235%86%
1440
21st to endNight
11111115%88%
1440
July1st to 10thNight
121223485%
1440
11th to 20thNight
111212335%80%
1440
21st to endNight
1112213345%77%
1894
August1st to 10thNight
111121223482%
1790
11th to 20thNight
1111122488%
1780
21st to endNight
1111123386%
1980
September1st to 10thNight
1111123485%
1800
11th to 20thNight
112225%87%
1921
21st to endNight
1111225%84%
1980
October1st to 10thNight
1222334478%
1980
11th to 20thNight
1112322336%78%
2114
21st to endNight
1112212336%78%
2414
November1st to 10thNight
111232335%7%73%
2405
11th to 20thNight
121232435%7%70%
2470
21st to endNight
231332445%8%64%
2470
December1st to 10thNight
5%313424447%62%
2470
11th to 20thNight
4425%6%45%6%7%9%48%
3041
21st to endNight
5%425%6%36%6%7%10%47%
4809

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
24%6%8%22%27%13%
1519
11th to 20thDay
22%49%18%29%19%
1600
21st to endDay
27%48%20%22%19%
1936
February1st to 10thDay
21%46%20%27%23%
1800
11th to 20thDay
19%46%18%34%19%
1760
21st to endDay
22%5%9%19%28%16%
1480
March1st to 10thDay
24%6%13%19%21%17%
1800
11th to 20thDay
20%6%10%20%26%17%
1852
21st to endDay
18%6%12%25%27%12%
2376
April1st to 10thDay
19%411%24%26%16%
2160
11th to 20thDay
13%311%21%33%20%
2132
21st to endDay
11%411%24%36%16%
2160
May1st to 10thDay
11%311%22%31%22%
2222
11th to 20thDay
10%28%20%37%22%
2304
21st to endDay
11%28%25%36%17%
2530
June1st to 10thDay
9%38%16%32%33%
2420
11th to 20thDay
416%13%26%49%
2520
21st to endDay
6%125%22%63%
2520
July1st to 10thDay
6%237%18%65%
2451
11th to 20thDay
10%1312%28%46%
2445
21st to endDay
9%35%16%31%36%
2282
August1st to 10thDay
8%128%22%58%
2135
11th to 20thDay
5%127%31%54%
2122
21st to endDay
7%137%28%55%
2376
September1st to 10thDay
7%247%24%55%
2160
11th to 20thDay
41210%32%51%
2039
21st to endDay
7%138%37%43%
1980
October1st to 10thDay
11%35%16%26%40%
1980
11th to 20thDay
9%3413%30%42%
1841
21st to endDay
9%35%12%27%44%
1940
November1st to 10thDay
11%37%17%34%28%
1674
11th to 20thDay
14%37%16%28%31%
1710
21st to endDay
19%47%16%27%27%
1710
December1st to 10thDay
22%5%9%19%24%21%
1710
11th to 20thDay
32%7%10%19%22%10%
2168
21st to endDay
34%7%7%23%20%9%
2844
January1st to 10thNight
23%6%8%19%29%14%
2646
11th to 20thNight
19%5%9%20%29%19%
2445
21st to endNight
24%311%16%24%21%
2416
February1st to 10thNight
20%5%8%16%25%26%
2160
11th to 20thNight
20%47%17%28%24%
2099
21st to endNight
19%5%12%19%28%17%
1776
March1st to 10thNight
21%6%14%22%21%16%
2160
11th to 20thNight
18%7%13%17%27%17%
2102
21st to endNight
18%5%13%28%25%11%
1980
April1st to 10thNight
17%6%12%27%22%16%
1800
11th to 20thNight
12%311%27%28%19%
1779
21st to endNight
11%311%26%37%13%
1800
May1st to 10thNight
8%5%14%23%31%19%
1736
11th to 20thNight
8%38%22%40%19%
1595
21st to endNight
7%311%30%37%13%
1746
June1st to 10thNight
7%310%21%29%30%
1534
11th to 20thNight
325%16%28%46%
1440
21st to endNight
4136%27%59%
1440
July1st to 10thNight
5%228%22%62%
1400
11th to 20thNight
9%3412%26%46%
1392
21st to endNight
10%25%14%31%38%
1789
August1st to 10thNight
7%139%23%55%
1780
11th to 20thNight
5%127%31%54%
1780
21st to endNight
5%227%30%54%
1980
September1st to 10thNight
6%137%28%55%
1800
11th to 20thNight
41310%34%48%
1921
21st to endNight
5%1310%37%44%
1980
October1st to 10thNight
11%25%14%27%40%
1980
11th to 20thNight
10%26%12%31%40%
2114
21st to endNight
10%4411%26%46%
2414
November1st to 10thNight
11%36%17%32%31%
2405
11th to 20thNight
13%27%15%29%33%
2470
21st to endNight
18%5%8%18%24%28%
2470
December1st to 10thNight
21%48%17%26%24%
2470
11th to 20thNight
26%11%12%15%24%12%
3041
21st to endNight
27%7%11%25%21%9%
4809

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
6%15%35%32%12%
180
11th to 20thDay
11%18%28%30%13%1
296
21st to endDay
7%22%29%27%13%2
443
February1st to 10thDay
5%20%31%28%13%3
420
11th to 20thDay
7%22%35%23%10%2
415
21st to endDay
6%23%33%27%10%1
346
March1st to 10thDay
8%25%32%22%10%1
420
11th to 20thDay
7%20%34%25%12%2
420
21st to endDay
7%25%34%23%10%1
462
April1st to 10thDay
8%16%32%29%12%3
420
11th to 20thDay
322%37%24%10%3
412
21st to endDay
320%34%24%13%6%
420
May1st to 10thDay
415%36%26%15%4
423
11th to 20thDay
215%33%32%13%5%
448
21st to endDay
412%34%29%14%6%
485
June1st to 10thDay
19%29%33%19%8%
450
11th to 20thDay
16%30%33%21%8%
450
21st to endDay
15%28%36%21%9%
450
July1st to 10thDay
1122%46%22%8%
446
11th to 20thDay
115%44%27%12%
444
21st to endDay
2115%43%26%14%
487
August1st to 10thDay
2224%44%21%8%
447
11th to 20thDay
1217%42%27%11%
437
21st to endDay
119%44%25%10%
495
September1st to 10thDay
1223%40%27%8%
450
11th to 20thDay
16%28%39%22%5%
450
21st to endDay
8%25%34%25%8%
450
October1st to 10thDay
110%30%34%22%3
450
11th to 20thDay
18%25%40%23%3
450
21st to endDay
212%28%29%23%5%
455
November1st to 10thDay
111%26%34%24%5%
270
11th to 20thDay
310%25%41%18%3
270
21st to endDay
314%29%36%16%3
270
December1st to 10thDay
6%10%31%36%15%2
270
11th to 20thDay
6%14%26%36%16%2
270
21st to endDay
10%24%21%31%11%2
210
January1st to 10thNight
6%10%27%38%16%3
760
11th to 20thNight
47%33%39%16%1
736
21st to endNight
7%10%31%36%14%2
792
February1st to 10thNight
38%32%36%19%3
720
11th to 20thNight
5%8%31%36%17%4
704
21st to endNight
5%8%35%38%13%2
592
March1st to 10thNight
410%34%38%14%1
720
11th to 20thNight
47%27%36%21%4
720
21st to endNight
48%31%40%16%1
792
April1st to 10thNight
46%32%37%20%2
720
11th to 20thNight
26%36%37%18%1
711
21st to endNight
26%32%37%20%3
720
May1st to 10thNight
435%42%16%2
656
11th to 20thNight
5%28%40%25%1
531
21st to endNight
17%31%40%20%1
584
June1st to 10thNight
322%51%24%1
454
11th to 20thNight
117%54%26%2
360
21st to endNight
13%50%36%1
360
July1st to 10thNight
1248%46%3
350
11th to 20thNight
11244%50%3
348
21st to endNight
11441%47%5%
712
August1st to 10thNight
116%47%39%5%
716
11th to 20thNight
1437%51%8%
712
21st to endNight
1440%45%9%
792
September1st to 10thNight
118%36%46%8%
720
11th to 20thNight
110%47%37%6%
720
21st to endNight
116%40%36%7%
720
October1st to 10thNight
1220%49%27%2
720
11th to 20thNight
1319%43%29%5%
720
21st to endNight
2424%37%26%8%
792
November1st to 10thNight
15%22%42%26%5%
740
11th to 20thNight
2323%43%23%6%
760
21st to endNight
35%26%42%22%2
760
December1st to 10thNight
6%6%30%38%18%2
760
11th to 20thNight
7%7%27%42%17%1
760
21st to endNight
6%9%32%38%13%2
836
Page generated at 2024-01-11 19:33:47. Version ac07

Copyright 2024 Attilla Danko


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