Lizard Hollow Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lizard Hollow Observatory clear sky chart from 2005-11-06 to 2024-01-16.

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
72%
24003
37%
74347
32%
23953
79%
23953
53%
35028

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
65%
758
35%
2457
31%
756
74%
756
49%
1158
January11th to 20thNight
67%
744
38%
2418
34%
744
76%
744
51%
1121
January21st to endNight
63%
792
36%
2574
33%
792
73%
792
42%
1310
February1st to 10thNight
69%
720
38%
2287
36%
720
77%
720
53%
1051
February11th to 20thNight
62%
700
35%
2099
29%
700
72%
700
47%
1069
February21st to endNight
59%
592
40%
1696
31%
592
71%
592
52%
855
March1st to 10thNight
59%
720
39%
1980
28%
720
71%
720
54%
1004
March11th to 20thNight
67%
720
39%
1980
29%
720
75%
720
58%
969
March21st to endNight
68%
792
39%
2178
27%
792
77%
792
57%
1084
April1st to 10thNight
70%
720
39%
1980
27%
720
79%
720
67%
900
April11th to 20thNight
65%
579
42%
1823
33%
579
77%
579
63%
745
April21st to endNight
72%
540
47%
1764
40%
540
82%
540
71%
658
May1st to 10thNight
71%
540
43%
1620
33%
540
80%
540
71%
649
May11th to 20thNight
76%
531
43%
1594
36%
531
81%
531
71%
648
May21st to endNight
78%
582
44%
1746
37%
582
82%
582
81%
659
June1st to 10thNight
82%
540
37%
1620
32%
540
83%
540
68%
680
June11th to 20thNight
83%
540
40%
1620
33%
540
85%
540
79%
625
June21st to endNight
82%
540
32%
1620
26%
540
84%
540
59%
735
July1st to 10thNight
80%
525
25%
1575
21%
525
80%
525
45%
821
July11th to 20thNight
83%
522
22%
1566
18%
522
83%
522
39%
875
July21st to endNight
78%
591
18%
1674
15%
558
77%
558
30%
1044
August1st to 10thNight
86%
537
26%
1602
24%
534
86%
534
48%
825
August11th to 20thNight
80%
534
30%
1602
29%
534
80%
534
40%
875
August21st to endNight
85%
645
31%
2021
32%
645
85%
645
44%
1051
September1st to 10thNight
79%
720
32%
1980
28%
720
80%
720
46%
1103
September11th to 20thNight
83%
720
40%
1980
34%
720
84%
720
60%
967
September21st to endNight
77%
720
40%
1980
29%
720
82%
720
60%
953
October1st to 10thNight
77%
720
40%
2047
32%
720
83%
720
63%
952
October11th to 20thNight
78%
720
45%
2160
35%
720
87%
720
71%
882
October21st to endNight
79%
792
46%
2376
39%
792
85%
792
72%
971
November1st to 10thNight
74%
740
46%
2220
38%
740
82%
740
67%
941
November11th to 20thNight
77%
760
44%
2311
37%
760
84%
760
64%
994
November21st to endNight
64%
760
38%
2470
33%
760
74%
760
48%
1185
December1st to 10thNight
67%
760
39%
2470
36%
760
75%
760
51%
1146
December11th to 20thNight
62%
759
34%
2928
33%
758
71%
758
35%
1542
December21st to endNight
62%
828
24%
4329
34%
817
69%
817
28%
1981

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
421332345%6%67%
74994
Night
4213323446%67%
74858
TransparencyDay
19%3412%24%37%
74721
Night
18%3413%25%35%
74653
SeeingDay
6%6%22%34%24%9%
13803
Night
5%215%44%30%4
24020

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
6%314423347%63%
1708
11th to 20thDay
6%112333446%66%
1669
21st to endDay
6%413324445%64%
1782
February1st to 10thDay
6%213222236%69%
1670
11th to 20thDay
9%414423436%61%
1750
21st to endDay
7%323212335%67%
1560
March1st to 10thDay
5%213324446%64%
1980
11th to 20thDay
5%313323345%68%
1980
21st to endDay
321232324474%
2178
April1st to 10thDay
2111222347%75%
1980
11th to 20thDay
221221123480%
2082
21st to endDay
211221223481%
2191
May1st to 10thDay
111121224480%
2340
11th to 20thDay
111221334479%
2301
21st to endDay
11111112387%
2530
June1st to 10thDay
2212212247%77%
2340
11th to 20thDay
11221223485%
2340
21st to endDay
221332435%6%69%
2340
July1st to 10thDay
3214446%7%7%8%54%
2340
11th to 20thDay
3326%6%46%7%10%13%39%
2340
21st to endDay
7%5%37%8%48%6%10%11%33%
2545
August1st to 10thDay
5%326%5%36%6%7%8%49%
2328
11th to 20thDay
4225%5%36%6%8%10%48%
2299
21st to endDay
32145%46%6%7%8%53%
2330
September1st to 10thDay
6%3244245%5%7%57%
1980
11th to 20thDay
3212324346%71%
1980
21st to endDay
3212323435%72%
1980
October1st to 10thDay
2112323346%73%
1911
11th to 20thDay
211111123482%
1800
21st to endDay
1112222336%78%
1980
November1st to 10thDay
2112212247%77%
1859
11th to 20thDay
2212223445%73%
1866
21st to endDay
5%314324447%64%
1710
December1st to 10thDay
6%31342445%7%62%
1710
11th to 20thDay
6%5%25%43447%7%53%
2169
21st to endDay
7%424433345%61%
3146
January1st to 10thNight
6%31332445%7%64%
2457
11th to 20thNight
6%313223345%68%
2418
21st to endNight
6%424424445%61%
2574
February1st to 10thNight
6%213313345%68%
2287
11th to 20thNight
7%313423446%63%
2098
21st to endNight
7%313224345%66%
1696
March1st to 10thNight
5%213324447%65%
1980
11th to 20thNight
5%22231324471%
1980
21st to endNight
3313322336%69%
2178
April1st to 10thNight
2112223346%75%
1980
11th to 20thNight
211222233479%
1823
21st to endNight
311111122484%
1764
May1st to 10thNight
111213246%79%
1620
11th to 20thNight
111221233480%
1594
21st to endNight
11111112388%
1746
June1st to 10thNight
2111213345%77%
1620
11th to 20thNight
21111215%85%
1620
21st to endNight
2212324446%71%
1620
July1st to 10thNight
3224435%6%6%9%56%
1620
11th to 20thNight
32145%47%7%10%15%42%
1620
21st to endNight
4435%6%47%9%10%16%34%
1773
August1st to 10thNight
22134246%8%9%56%
1611
11th to 20thNight
34145%46%5%7%9%52%
1602
21st to endNight
33235%346%9%12%51%
2021
September1st to 10thNight
5%415%43446%9%56%
1980
11th to 20thNight
2213423346%71%
1980
21st to endNight
2212433345%71%
1980
October1st to 10thNight
2212322346%73%
2047
11th to 20thNight
2111112235%80%
2160
21st to endNight
111121222482%
2376
November1st to 10thNight
2112212345%76%
2220
11th to 20thNight
3211313335%75%
2311
21st to endNight
6%313323346%64%
2470
December1st to 10thNight
6%323222447%65%
2470
11th to 20thNight
7%425%5%34446%57%
3041
21st to endNight
8%5%134245%45%58%
4521

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
23%2316%30%26%
1709
11th to 20thDay
21%3312%29%33%
1669
21st to endDay
23%3216%27%29%
1782
February1st to 10thDay
20%2312%24%41%
1670
11th to 20thDay
26%3313%24%30%
1760
21st to endDay
22%2211%29%34%
1560
March1st to 10thDay
21%2210%30%35%
1980
11th to 20thDay
19%329%26%41%
1980
21st to endDay
16%319%33%38%
2178
April1st to 10thDay
11%216%34%45%
1980
11th to 20thDay
10%26%25%56%
2085
21st to endDay
9%217%26%55%
2191
May1st to 10thDay
10%117%20%60%
2340
11th to 20thDay
10%229%21%56%
2304
21st to endDay
7%1422%67%
2530
June1st to 10thDay
10%21422%60%
2340
11th to 20thDay
7%2216%73%
2340
21st to endDay
16%348%18%51%
2340
July1st to 10thDay
24%6%9%13%18%29%
2276
11th to 20thDay
31%7%18%23%14%7%
2271
21st to endDay
38%9%17%21%11%4
2404
August1st to 10thDay
29%6%12%17%19%18%
2313
11th to 20thDay
27%7%14%18%20%14%
2299
21st to endDay
27%7%10%21%20%17%
2330
September1st to 10thDay
26%47%20%19%23%
1980
11th to 20thDay
16%4312%26%40%
1980
21st to endDay
16%4310%30%38%
1980
October1st to 10thDay
12%3414%27%39%
1911
11th to 20thDay
9%129%25%54%
1800
21st to endDay
11%239%26%49%
1980
November1st to 10thDay
9%2212%36%39%
1859
11th to 20thDay
14%2211%29%42%
1866
21st to endDay
22%2312%26%35%
1710
December1st to 10thDay
23%2415%28%27%
1710
11th to 20thDay
29%3419%24%21%
2168
21st to endDay
25%4318%32%19%
3146
January1st to 10thNight
21%3417%32%24%
2457
11th to 20thNight
19%3314%29%31%
2418
21st to endNight
25%4313%31%24%
2574
February1st to 10thNight
19%2313%22%40%
2287
11th to 20thNight
23%3415%24%31%
2099
21st to endNight
21%3210%32%33%
1696
March1st to 10thNight
20%3213%27%35%
1980
11th to 20thNight
18%2211%23%44%
1980
21st to endNight
17%3212%33%33%
2178
April1st to 10thNight
12%229%33%42%
1980
11th to 20thNight
12%118%26%52%
1823
21st to endNight
9%116%28%55%
1764
May1st to 10thNight
9%238%23%55%
1620
11th to 20thNight
9%238%22%55%
1595
21st to endNight
5%15%23%65%
1746
June1st to 10thNight
11%215%22%59%
1620
11th to 20thNight
7%11316%72%
1620
21st to endNight
15%437%17%55%
1620
July1st to 10thNight
22%6%10%14%15%32%
1575
11th to 20thNight
25%9%18%26%14%7%
1566
21st to endNight
32%11%22%19%11%4
1674
August1st to 10thNight
20%7%14%22%18%19%
1602
11th to 20thNight
26%6%15%20%19%14%
1602
21st to endNight
22%6%13%22%20%16%
2021
September1st to 10thNight
25%5%8%23%17%22%
1980
11th to 20thNight
15%4413%28%36%
1980
21st to endNight
16%3311%30%37%
1980
October1st to 10thNight
14%3416%24%39%
2047
11th to 20thNight
9%2212%25%51%
2160
21st to endNight
9%2210%27%50%
2376
November1st to 10thNight
12%2212%32%40%
2220
11th to 20thNight
13%2212%30%40%
2311
21st to endNight
22%3312%28%33%
2470
December1st to 10thNight
20%2418%26%29%
2470
11th to 20thNight
29%3417%26%21%
3041
21st to endNight
26%5%316%29%20%
4521

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
11%5%28%36%18%2
270
11th to 20thDay
11%230%35%16%7%
257
21st to endDay
5%6%24%39%22%4
264
February1st to 10thDay
6%7%29%33%20%6%
290
11th to 20thDay
15%10%32%30%11%1
415
21st to endDay
14%13%35%26%10%2
346
March1st to 10thDay
8%13%36%29%10%4
420
11th to 20thDay
8%10%33%27%13%8%
420
21st to endDay
7%15%35%27%12%4
462
April1st to 10thDay
413%30%28%20%6%
420
11th to 20thDay
5%15%31%31%15%3
412
21st to endDay
314%29%32%18%5%
420
May1st to 10thDay
312%28%34%16%6%
423
11th to 20thDay
27%28%40%17%6%
448
21st to endDay
26%29%38%20%4
485
June1st to 10thDay
4420%42%22%8%
450
11th to 20thDay
2220%44%24%8%
450
21st to endDay
3117%40%28%10%
450
July1st to 10thDay
317%37%37%15%
446
11th to 20thDay
42432%38%20%
444
21st to endDay
7%2327%39%22%
487
August1st to 10thDay
41430%42%18%
447
11th to 20thDay
5%1428%41%21%
437
21st to endDay
32331%36%25%
495
September1st to 10thDay
8%211%38%30%12%
450
11th to 20thDay
3214%40%30%12%
450
21st to endDay
5%5%21%32%27%10%
450
October1st to 10thDay
3425%34%24%10%
381
11th to 20thDay
3322%34%29%10%
270
21st to endDay
2324%31%30%10%
297
November1st to 10thDay
46%26%37%23%4
270
11th to 20thDay
45%22%39%26%4
270
21st to endDay
6%430%39%17%4
270
December1st to 10thDay
8%229%31%27%3
270
11th to 20thDay
9%429%41%15%2
270
21st to endDay
13%5%29%31%18%4
297
January1st to 10thNight
8%121%46%21%3
760
11th to 20thNight
7%219%44%24%4
744
21st to endNight
8%319%47%21%2
792
February1st to 10thNight
6%218%46%22%6%
720
11th to 20thNight
8%319%51%16%2
704
21st to endNight
8%325%47%15%1
592
March1st to 10thNight
6%327%46%17%1
720
11th to 20thNight
5%321%41%25%5%
720
21st to endNight
4320%49%23%2
792
April1st to 10thNight
2321%53%20%2
720
11th to 20thNight
35%23%51%17%1
579
21st to endNight
3320%54%18%2
540
May1st to 10thNight
2321%51%21%1
540
11th to 20thNight
1217%52%27%1
531
21st to endNight
1217%53%26%1
584
June1st to 10thNight
2211%54%30%1
540
11th to 20thNight
2111%53%32%1
540
21st to endNight
218%44%45%1
540
July1st to 10thNight
315%33%54%3
525
11th to 20thNight
21223%64%8%
522
21st to endNight
5%1224%53%13%
591
August1st to 10thNight
31124%58%12%
537
11th to 20thNight
42225%59%7%
534
21st to endNight
31225%58%11%
645
September1st to 10thNight
6%25%30%48%10%
720
11th to 20thNight
217%41%42%7%
720
21st to endNight
3112%43%37%4
720
October1st to 10thNight
3114%47%32%3
720
11th to 20thNight
2215%47%31%4
720
21st to endNight
2114%46%29%7%
792
November1st to 10thNight
3117%43%31%5%
740
11th to 20thNight
4115%46%31%3
760
21st to endNight
8%221%45%21%4
760
December1st to 10thNight
8%117%46%23%4
760
11th to 20thNight
8%320%49%17%3
760
21st to endNight
10%219%45%20%5%
836
Page generated at 2024-01-13 17:28:27. Version ac07

Copyright 2024 Attilla Danko


Lizard Hollow Observatory Clear Sky Chart |Charts Home