Lagoon Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lagoon Observatory clear sky chart from 2005-11-06 to 2024-01-14.

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
71%
24343
33%
74558
28%
24289
77%
24289
46%
37793

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
58%
759
28%
2608
25%
756
67%
756
36%
1326
January11th to 20thNight
59%
734
36%
2384
27%
734
74%
734
44%
1167
January21st to endNight
53%
792
37%
2481
27%
792
68%
792
38%
1273
February1st to 10thNight
62%
720
38%
2160
31%
720
72%
720
43%
1116
February11th to 20thNight
62%
700
34%
2098
30%
700
71%
700
43%
1099
February21st to endNight
56%
592
30%
1776
27%
592
65%
592
39%
949
March1st to 10thNight
58%
720
27%
2160
23%
720
68%
720
39%
1172
March11th to 20thNight
66%
720
25%
2048
22%
720
71%
720
41%
1142
March21st to endNight
68%
792
32%
2003
23%
792
73%
792
52%
1095
April1st to 10thNight
70%
720
30%
1800
21%
720
73%
720
48%
1028
April11th to 20thNight
69%
711
34%
1779
19%
711
74%
711
53%
960
April21st to endNight
74%
720
32%
1800
18%
720
77%
720
54%
972
May1st to 10thNight
74%
720
27%
1800
16%
720
75%
720
51%
1007
May11th to 20thNight
74%
552
29%
1616
22%
552
75%
552
45%
850
May21st to endNight
77%
582
29%
1746
23%
582
79%
582
54%
840
June1st to 10thNight
75%
400
26%
1480
26%
400
77%
400
37%
745
June11th to 20thNight
85%
360
32%
1440
38%
360
85%
360
48%
593
June21st to endNight
83%
360
33%
1440
41%
360
83%
360
46%
607
July1st to 10thNight
87%
350
35%
1400
41%
350
88%
350
52%
541
July11th to 20thNight
84%
418
32%
1462
33%
418
84%
418
50%
629
July21st to endNight
84%
705
32%
1782
24%
666
86%
666
57%
893
August1st to 10thNight
83%
716
32%
1780
21%
712
83%
712
58%
941
August11th to 20thNight
84%
712
35%
1780
22%
712
84%
712
60%
931
August21st to endNight
87%
792
36%
1980
25%
792
87%
792
65%
985
September1st to 10thNight
84%
720
36%
1800
29%
720
84%
720
60%
939
September11th to 20thNight
85%
720
40%
1885
36%
720
85%
720
62%
929
September21st to endNight
85%
720
40%
1980
38%
720
87%
720
64%
923
October1st to 10thNight
81%
720
38%
1995
36%
720
85%
720
61%
952
October11th to 20thNight
79%
720
38%
2160
40%
720
81%
720
52%
1042
October21st to endNight
76%
792
41%
2376
41%
792
81%
792
58%
1077
November1st to 10thNight
74%
740
36%
2373
35%
740
81%
740
52%
1065
November11th to 20thNight
71%
760
37%
2470
35%
760
79%
760
51%
1128
November21st to endNight
63%
760
35%
2470
33%
760
70%
760
44%
1195
December1st to 10thNight
58%
760
33%
2470
28%
760
68%
760
39%
1255
December11th to 20thNight
55%
760
29%
3019
28%
759
67%
759
26%
1800
December21st to endNight
58%
824
20%
4757
28%
817
68%
817
20%
2627

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
5%42332335%8%63%
74824
Night
6%424323347%62%
74927
TransparencyDay
22%39%19%26%21%
74546
Night
23%38%17%25%24%
74726
SeeingDay
6%7%21%36%24%6%
14480
Night
7%310%30%36%13%
24362

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
10%32443445%7%55%
1554
11th to 20thDay
8%314423336%62%
1648
21st to endDay
11%423312236%61%
1872
February1st to 10thDay
10%423322345%63%
1800
11th to 20thDay
7%31232336%7%61%
1750
21st to endDay
7%324423346%63%
1480
March1st to 10thDay
7%424435%5%5%7%54%
1800
11th to 20thDay
7%5%2332346%9%55%
1908
21st to endDay
6%21332445%8%63%
2351
April1st to 10thDay
6%42332335%8%59%
2160
11th to 20thDay
4423223447%67%
2129
21st to endDay
4314312348%67%
2160
May1st to 10thDay
45%2332335%9%62%
2160
11th to 20thDay
442321345%9%62%
2278
21st to endDay
341432335%9%63%
2530
June1st to 10thDay
46%3432446%8%56%
2474
11th to 20thDay
3424323347%65%
2520
21st to endDay
2413313448%67%
2520
July1st to 10thDay
331332335%9%65%
2520
11th to 20thDay
3312322348%69%
2445
21st to endDay
221332346%10%62%
2430
August1st to 10thDay
242322336%8%65%
2149
11th to 20thDay
2312212448%70%
2122
21st to endDay
121331335%8%70%
2376
September1st to 10thDay
2313313347%72%
2160
11th to 20thDay
3313212348%70%
2075
21st to endDay
221431235%6%71%
1980
October1st to 10thDay
4312222347%70%
1961
11th to 20thDay
4313212446%69%
1800
21st to endDay
3213213446%71%
1980
November1st to 10thDay
322432235%7%67%
1703
11th to 20thDay
4313223447%67%
1710
21st to endDay
4224323348%65%
1710
December1st to 10thDay
7%4243245%5%8%56%
1710
11th to 20thDay
14%5%26%43345%7%47%
2105
21st to endDay
12%5%15%6%345%6%7%46%
2794
January1st to 10thNight
9%42332435%8%55%
2608
11th to 20thNight
7%323323346%64%
2384
21st to endNight
10%424322336%62%
2481
February1st to 10thNight
7%5%24313346%63%
2160
11th to 20thNight
8%424323335%63%
2098
21st to endNight
11%423323335%61%
1776
March1st to 10thNight
8%5%243235%6%8%54%
2160
11th to 20thNight
6%5%245%2445%6%57%
2048
21st to endNight
6%423223348%62%
2003
April1st to 10thNight
6%5%23423447%60%
1800
11th to 20thNight
4423323336%67%
1779
21st to endNight
4413323447%65%
1800
May1st to 10thNight
5%5%23323347%62%
1800
11th to 20thNight
46%24323236%64%
1615
21st to endNight
3422212246%71%
1746
June1st to 10thNight
3435%5%2335%7%58%
1480
11th to 20thNight
233331335%7%67%
1440
21st to endNight
242442345%9%61%
1440
July1st to 10thNight
332332336%8%65%
1440
11th to 20thNight
231442446%9%63%
1510
21st to endNight
23243235%6%9%60%
1887
August1st to 10thNight
232442325%10%63%
1790
11th to 20thNight
232431345%8%63%
1780
21st to endNight
121432345%8%66%
1980
September1st to 10thNight
242332445%9%63%
1800
11th to 20thNight
322432225%7%68%
1885
21st to endNight
1323222345%73%
1980
October1st to 10thNight
3213213346%71%
1995
11th to 20thNight
5%423222236%69%
2160
21st to endNight
3423212335%72%
2376
November1st to 10thNight
332331335%7%68%
2373
11th to 20thNight
3324322336%68%
2470
21st to endNight
5%213424447%63%
2470
December1st to 10thNight
8%425%323246%60%
2470
11th to 20thNight
16%6%2442335%7%46%
3081
21st to endNight
13%5%25%5%445%46%47%
4862

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%29%17%23%19%
1554
11th to 20thDay
25%38%14%24%26%
1648
21st to endDay
27%36%20%18%26%
1872
February1st to 10thDay
25%4416%25%26%
1800
11th to 20thDay
23%37%16%27%23%
1760
21st to endDay
25%38%21%23%20%
1480
March1st to 10thDay
29%410%20%18%20%
1800
11th to 20thDay
26%5%12%19%24%15%
1908
21st to endDay
21%5%12%25%24%12%
2351
April1st to 10thDay
24%414%26%20%12%
2160
11th to 20thDay
19%39%26%28%16%
2132
21st to endDay
19%413%23%30%11%
2160
May1st to 10thDay
21%5%14%21%25%13%
2160
11th to 20thDay
22%6%10%24%27%11%
2281
21st to endDay
21%5%12%31%25%6%
2530
June1st to 10thDay
25%6%14%18%27%10%
2474
11th to 20thDay
21%410%15%32%18%
2520
21st to endDay
18%29%12%31%27%
2520
July1st to 10thDay
20%38%14%23%33%
2451
11th to 20thDay
17%38%20%30%22%
2370
21st to endDay
21%311%23%27%15%
2295
August1st to 10thDay
19%29%14%30%25%
2135
11th to 20thDay
16%18%15%34%24%
2122
21st to endDay
15%29%13%32%29%
2376
September1st to 10thDay
16%27%14%30%30%
2160
11th to 20thDay
17%28%15%29%29%
2075
21st to endDay
17%28%18%30%25%
1980
October1st to 10thDay
15%39%22%22%29%
1961
11th to 20thDay
19%37%15%26%30%
1800
21st to endDay
17%37%15%23%36%
1980
November1st to 10thDay
20%27%18%22%31%
1703
11th to 20thDay
18%48%15%19%37%
1710
21st to endDay
20%38%14%24%31%
1710
December1st to 10thDay
27%5%5%18%22%23%
1710
11th to 20thDay
37%48%15%20%15%
2104
21st to endDay
35%6%11%21%15%11%
2794
January1st to 10thNight
28%37%15%27%20%
2608
11th to 20thNight
23%37%16%22%29%
2384
21st to endNight
27%27%16%19%30%
2481
February1st to 10thNight
25%35%14%25%28%
2160
11th to 20thNight
26%3418%23%26%
2099
21st to endNight
28%37%17%23%23%
1776
March1st to 10thNight
28%49%19%23%17%
2160
11th to 20thNight
28%412%16%24%17%
2048
21st to endNight
21%411%26%24%14%
2003
April1st to 10thNight
26%313%26%20%12%
1800
11th to 20thNight
20%48%24%27%17%
1779
21st to endNight
20%312%23%29%13%
1800
May1st to 10thNight
23%412%24%24%13%
1800
11th to 20thNight
25%38%25%28%11%
1616
21st to endNight
17%411%31%30%7%
1746
June1st to 10thNight
27%5%12%21%27%8%
1480
11th to 20thNight
18%39%17%35%18%
1440
21st to endNight
21%28%11%31%28%
1440
July1st to 10thNight
16%37%11%24%40%
1400
11th to 20thNight
17%47%19%29%24%
1462
21st to endNight
18%310%26%27%16%
1782
August1st to 10thNight
19%25%12%32%29%
1780
11th to 20thNight
18%37%12%33%27%
1780
21st to endNight
15%27%12%34%30%
1980
September1st to 10thNight
19%28%10%27%35%
1800
11th to 20thNight
17%26%12%34%30%
1885
21st to endNight
15%16%13%34%31%
1980
October1st to 10thNight
16%26%19%25%32%
1995
11th to 20thNight
19%36%15%23%33%
2160
21st to endNight
17%25%12%23%41%
2376
November1st to 10thNight
17%36%15%24%35%
2373
11th to 20thNight
19%26%14%20%38%
2470
21st to endNight
23%36%17%20%32%
2470
December1st to 10thNight
26%36%16%20%29%
2470
11th to 20thNight
39%38%13%20%17%
3081
21st to endNight
37%6%8%22%17%12%
4862

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
17%433%35%11%
215
11th to 20thDay
12%8%29%38%11%2
350
21st to endDay
14%12%29%31%11%2
414
February1st to 10thDay
12%10%30%31%14%4
420
11th to 20thDay
10%11%31%34%11%3
415
21st to endDay
12%14%29%32%12%1
346
March1st to 10thDay
13%15%31%30%10%1
420
11th to 20thDay
12%10%31%29%16%2
420
21st to endDay
10%13%30%33%13%1
462
April1st to 10thDay
8%10%25%38%16%3
420
11th to 20thDay
6%15%26%35%13%5%
412
21st to endDay
48%27%35%20%5%
420
May1st to 10thDay
5%9%27%35%20%4
423
11th to 20thDay
6%6%22%40%22%4
448
21st to endDay
6%8%25%34%21%5%
485
June1st to 10thDay
6%5%20%35%26%8%
450
11th to 20thDay
3414%39%32%8%
450
21st to endDay
4213%37%36%8%
450
July1st to 10thDay
416%39%37%13%
446
11th to 20thDay
3330%46%18%
444
21st to endDay
1437%41%16%
487
August1st to 10thDay
39%41%34%12%
447
11th to 20thDay
316%37%41%13%
437
21st to endDay
127%42%38%10%
495
September1st to 10thDay
4113%42%30%10%
450
11th to 20thDay
4318%44%24%7%
450
21st to endDay
15%16%38%33%7%
450
October1st to 10thDay
4421%45%23%4
450
11th to 20thDay
5%421%45%20%5%
450
21st to endDay
47%23%36%23%7%
495
November1st to 10thDay
5%7%20%37%21%9%
299
11th to 20thDay
5%7%31%33%19%5%
270
21st to endDay
5%12%27%33%17%5%
270
December1st to 10thDay
10%11%26%34%16%3
270
11th to 20thDay
7%10%29%33%18%3
252
21st to endDay
14%10%33%28%14%3
198
January1st to 10thNight
12%5%17%40%20%6%
760
11th to 20thNight
9%6%21%40%22%2
734
21st to endNight
14%9%17%35%22%3
792
February1st to 10thNight
10%6%15%37%27%7%
720
11th to 20thNight
10%416%39%24%6%
704
21st to endNight
13%8%17%35%24%3
592
March1st to 10thNight
10%6%17%39%25%3
720
11th to 20thNight
8%413%35%31%8%
720
21st to endNight
9%415%36%33%4
792
April1st to 10thNight
8%311%38%35%6%
720
11th to 20thNight
6%5%13%34%35%8%
711
21st to endNight
6%410%34%37%10%
720
May1st to 10thNight
8%39%34%37%10%
720
11th to 20thNight
6%37%30%42%12%
552
21st to endNight
3310%31%42%12%
584
June1st to 10thNight
425%30%44%16%
400
11th to 20thNight
21319%55%20%
360
21st to endNight
41119%56%18%
360
July1st to 10thNight
41360%31%
350
11th to 20thNight
4443%48%
418
21st to endNight
418%49%37%
705
August1st to 10thNight
31114%53%28%
716
11th to 20thNight
31111%49%36%
712
21st to endNight
21112%54%31%
792
September1st to 10thNight
42217%48%27%
720
11th to 20thNight
31222%55%18%
720
21st to endNight
21423%51%19%
720
October1st to 10thNight
416%34%46%9%
720
11th to 20thNight
6%16%33%42%10%
720
21st to endNight
5%310%36%34%12%
792
November1st to 10thNight
5%410%38%31%11%
740
11th to 20thNight
4313%39%31%10%
760
21st to endNight
6%5%19%37%29%5%
760
December1st to 10thNight
8%7%18%38%24%6%
760
11th to 20thNight
13%6%18%39%20%4
760
21st to endNight
11%8%17%39%21%4
836
Page generated at 2024-01-11 01:22:43. Version ac07

Copyright 2024 Attilla Danko


Lagoon Observatory Clear Sky Chart |Charts Home