Hensley Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hensley Lake 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
71%
23708
32%
74672
29%
23665
75%
23665
48%
36991

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%
757
17%
2646
19%
756
60%
756
27%
1596
January11th to 20thNight
67%
732
24%
2431
25%
732
70%
732
33%
1368
January21st to endNight
66%
792
26%
2574
29%
792
68%
792
33%
1489
February1st to 10thNight
65%
720
27%
2272
28%
720
68%
720
37%
1248
February11th to 20thNight
66%
700
31%
2099
32%
700
70%
700
44%
1109
February21st to endNight
61%
592
26%
1776
27%
592
64%
592
35%
1038
March1st to 10thNight
57%
720
20%
2160
20%
720
61%
720
34%
1278
March11th to 20thNight
60%
720
25%
1998
23%
720
63%
720
40%
1164
March21st to endNight
59%
792
24%
2039
16%
792
64%
792
45%
1187
April1st to 10thNight
57%
720
29%
1800
15%
720
64%
720
48%
1014
April11th to 20thNight
58%
711
33%
1779
14%
711
65%
711
53%
956
April21st to endNight
61%
720
32%
1800
14%
720
66%
720
59%
934
May1st to 10thNight
63%
684
32%
1764
17%
684
69%
684
62%
868
May11th to 20thNight
64%
496
37%
1559
27%
496
71%
496
60%
664
May21st to endNight
62%
389
33%
1552
27%
388
75%
388
54%
585
June1st to 10thNight
65%
360
35%
1440
33%
360
78%
360
56%
520
June11th to 20thNight
72%
360
41%
1440
42%
360
85%
360
76%
424
June21st to endNight
78%
360
41%
1440
45%
360
88%
360
79%
427
July1st to 10thNight
85%
350
41%
1400
46%
350
92%
350
82%
401
July11th to 20thNight
87%
348
42%
1392
49%
348
91%
348
69%
451
July21st to endNight
87%
558
42%
1643
35%
527
90%
527
68%
673
August1st to 10thNight
84%
628
40%
1693
26%
625
86%
625
78%
717
August11th to 20thNight
88%
712
40%
1780
24%
712
90%
712
81%
806
August21st to endNight
92%
792
45%
1980
29%
792
93%
792
86%
866
September1st to 10thNight
90%
720
47%
1800
33%
720
92%
720
86%
780
September11th to 20thNight
83%
720
48%
1836
37%
720
88%
720
79%
815
September21st to endNight
83%
720
45%
1980
40%
720
88%
720
76%
840
October1st to 10thNight
80%
720
36%
2105
36%
720
85%
720
64%
926
October11th to 20thNight
83%
720
41%
2160
44%
720
86%
720
65%
928
October21st to endNight
82%
792
45%
2376
46%
792
87%
792
68%
997
November1st to 10thNight
76%
740
33%
2400
37%
740
78%
740
49%
1155
November11th to 20thNight
79%
760
34%
2470
36%
760
82%
760
52%
1135
November21st to endNight
73%
760
32%
2470
34%
760
76%
760
43%
1249
December1st to 10thNight
64%
760
24%
2603
26%
760
67%
760
33%
1463
December11th to 20thNight
63%
760
20%
3217
26%
759
65%
759
21%
2057
December21st to endNight
58%
823
14%
4798
24%
817
62%
817
16%
2863

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
7%313323345%67%
74773
Night
8%313323346%65%
74987
TransparencyDay
21%38%19%25%24%
74487
Night
23%39%21%24%21%
74795
SeeingDay
7%416%32%29%12%
14136
Night
9%213%38%31%7%
23728

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
15%7%45%6%35%5%5%7%40%
1519
11th to 20thDay
11%32443445%7%52%
1589
21st to endDay
16%5%25%5%35%5%48%42%
1782
February1st to 10thDay
14%4244245%5%6%51%
1685
11th to 20thDay
12%425%32446%6%52%
1750
21st to endDay
16%5%24424446%49%
1480
March1st to 10thDay
14%6%25%435%7%5%8%41%
1800
11th to 20thDay
13%5%344345%6%8%46%
1957
21st to endDay
12%5%1332345%7%54%
2316
April1st to 10thDay
10%42332335%6%59%
2160
11th to 20thDay
8%423323347%61%
2129
21st to endDay
6%222223447%65%
2160
May1st to 10thDay
3312323345%72%
2196
11th to 20thDay
4113223347%71%
2332
21st to endDay
5%21222335%7%69%
2723
June1st to 10thDay
3212212336%75%
2520
11th to 20thDay
11111122387%
2520
21st to endDay
11111122386%
2520
July1st to 10thDay
11111222487%
2520
11th to 20thDay
111111222385%
2520
21st to endDay
1111212335%79%
2575
August1st to 10thDay
2211222384%
2235
11th to 20thDay
11111122387%
2122
21st to endDay
11111112387%
2376
September1st to 10thDay
21111122288%
2160
11th to 20thDay
221111122484%
2124
21st to endDay
211111123482%
1980
October1st to 10thDay
2212323345%74%
1852
11th to 20thDay
311222333477%
1800
21st to endDay
5%212212245%73%
1980
November1st to 10thDay
7%312324448%61%
1676
11th to 20thDay
8%3234245%46%61%
1710
21st to endDay
10%423434446%58%
1710
December1st to 10thDay
14%423435%447%50%
1573
11th to 20thDay
22%7%35%5%34346%37%
1928
21st to endDay
13%7%48%7%45%5%6%8%34%
2794
January1st to 10thNight
16%6%35%5%23447%45%
2646
11th to 20thNight
11%42443445%7%52%
2431
21st to endNight
16%5%13323448%51%
2574
February1st to 10thNight
14%414323446%55%
2272
11th to 20thNight
11%323323447%58%
2098
21st to endNight
16%5%24322346%53%
1776
March1st to 10thNight
15%435%333446%50%
2160
11th to 20thNight
13%5%2342346%8%51%
1998
21st to endNight
12%414323436%58%
2039
April1st to 10thNight
10%41431335%7%60%
1800
11th to 20thNight
7%322314336%66%
1779
21st to endNight
5%212223435%71%
1800
May1st to 10thNight
3213213346%71%
1764
11th to 20thNight
5%112213235%75%
1558
21st to endNight
4213222235%76%
1552
June1st to 10thNight
3211222335%76%
1440
11th to 20thNight
1111222387%
1440
21st to endNight
111222388%
1440
July1st to 10thNight
111122389%
1440
11th to 20thNight
221111223382%
1440
21st to endNight
2112122336%77%
1740
August1st to 10thNight
121111112385%
1702
11th to 20thNight
11111222485%
1780
21st to endNight
11111112388%
1980
September1st to 10thNight
1111112389%
1800
11th to 20thNight
11111222385%
1836
21st to endNight
211111223384%
1980
October1st to 10thNight
321222323475%
2105
11th to 20thNight
3212212345%77%
2160
21st to endNight
5%112212235%79%
2376
November1st to 10thNight
8%323322337%66%
2400
11th to 20thNight
6%213323346%67%
2470
21st to endNight
9%314323447%61%
2470
December1st to 10thNight
13%5%24423346%53%
2603
11th to 20thNight
20%6%26%42345%7%39%
3276
21st to endNight
15%6%35%5%45%5%6%8%38%
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
46%6%14%21%11%2
1519
11th to 20thDay
33%6%13%21%17%9%
1589
21st to endDay
41%413%22%17%3
1782
February1st to 10thDay
33%411%27%18%7%
1685
11th to 20thDay
32%310%25%23%7%
1760
21st to endDay
36%412%29%18%2
1480
March1st to 10thDay
38%5%13%23%17%4
1800
11th to 20thDay
34%413%24%20%5%
1957
21st to endDay
30%416%28%18%5%
2316
April1st to 10thDay
27%313%28%21%9%
2160
11th to 20thDay
24%311%27%25%11%
2132
21st to endDay
20%310%29%30%8%
2160
May1st to 10thDay
16%210%24%35%14%
2196
11th to 20thDay
15%26%26%33%18%
2335
21st to endDay
16%28%31%31%12%
2724
June1st to 10thDay
13%28%21%31%24%
2520
11th to 20thDay
6%1415%36%38%
2520
21st to endDay
7%128%30%52%
2520
July1st to 10thDay
5%125%22%65%
2451
11th to 20thDay
7%128%24%58%
2445
21st to endDay
10%218%24%54%
2432
August1st to 10thDay
9%118%25%56%
2219
11th to 20thDay
6%117%30%55%
2122
21st to endDay
6%117%33%53%
2376
September1st to 10thDay
6%126%27%57%
2160
11th to 20thDay
8%1219%38%32%
2124
21st to endDay
8%1317%38%33%
1980
October1st to 10thDay
12%26%20%28%31%
1852
11th to 20thDay
13%25%24%29%28%
1800
21st to endDay
16%26%22%31%24%
1980
November1st to 10thDay
24%310%26%27%11%
1676
11th to 20thDay
25%412%28%25%6%
1710
21st to endDay
28%5%10%23%26%9%
1710
December1st to 10thDay
36%6%10%21%19%9%
1573
11th to 20thDay
50%5%10%19%13%4
1928
21st to endDay
48%6%17%18%8%2
2794
January1st to 10thNight
41%314%24%15%3
2646
11th to 20thNight
32%6%14%21%16%11%
2431
21st to endNight
34%5%13%22%20%6%
2574
February1st to 10thNight
31%311%25%21%8%
2272
11th to 20thNight
27%311%29%25%7%
2099
21st to endNight
35%311%30%18%4
1776
March1st to 10thNight
36%314%22%21%5%
2160
11th to 20thNight
32%312%24%23%7%
1998
21st to endNight
28%314%29%20%5%
2039
April1st to 10thNight
25%314%29%20%9%
1800
11th to 20thNight
21%212%27%28%9%
1779
21st to endNight
17%311%31%32%6%
1800
May1st to 10thNight
15%210%26%34%14%
1764
11th to 20thNight
14%27%27%34%16%
1559
21st to endNight
14%29%29%33%13%
1552
June1st to 10thNight
13%28%24%32%21%
1440
11th to 20thNight
5%1418%35%37%
1440
21st to endNight
5%129%27%56%
1440
July1st to 10thNight
411423%67%
1400
11th to 20thNight
9%116%23%60%
1392
21st to endNight
11%217%24%55%
1643
August1st to 10thNight
8%1110%25%55%
1693
11th to 20thNight
6%217%29%55%
1780
21st to endNight
5%116%31%56%
1980
September1st to 10thNight
5%127%25%61%
1800
11th to 20thNight
8%1215%40%34%
1836
21st to endNight
8%2114%38%37%
1980
October1st to 10thNight
14%25%18%26%35%
2105
11th to 20thNight
12%26%21%28%31%
2160
21st to endNight
12%1423%34%26%
2376
November1st to 10thNight
23%29%24%26%17%
2400
11th to 20thNight
20%211%29%26%12%
2470
21st to endNight
24%410%24%29%9%
2470
December1st to 10thNight
34%410%22%19%12%
2603
11th to 20thNight
44%5%13%18%15%4
3276
21st to endNight
46%317%23%9%3
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
25%318%32%17%5%
180
11th to 20thDay
16%411%35%23%13%
295
21st to endDay
17%214%31%26%10%
374
February1st to 10thDay
16%6%13%29%23%14%
370
11th to 20thDay
15%5%19%32%19%9%
415
21st to endDay
14%8%21%32%21%4
346
March1st to 10thDay
16%6%23%29%21%5%
420
11th to 20thDay
15%8%28%24%19%7%
420
21st to endDay
17%10%23%27%19%4
462
April1st to 10thDay
13%11%24%26%17%8%
420
11th to 20thDay
12%9%26%31%16%5%
412
21st to endDay
5%10%25%32%19%11%
420
May1st to 10thDay
49%28%33%18%7%
423
11th to 20thDay
5%6%27%33%22%7%
448
21st to endDay
6%7%17%35%27%9%
485
June1st to 10thDay
3423%31%30%10%
450
11th to 20thDay
2420%35%29%10%
450
21st to endDay
1315%38%29%15%
450
July1st to 10thDay
18%36%42%14%
446
11th to 20thDay
15%28%45%21%
444
21st to endDay
115%31%42%20%
487
August1st to 10thDay
411%37%33%14%
447
11th to 20thDay
1111%33%37%17%
437
21st to endDay
17%30%41%20%
495
September1st to 10thDay
129%36%36%16%
450
11th to 20thDay
4218%35%31%10%
450
21st to endDay
2314%31%37%14%
450
October1st to 10thDay
3319%32%28%15%
450
11th to 20thDay
45%15%28%35%14%
450
21st to endDay
5%313%28%35%15%
495
November1st to 10thDay
10%315%26%31%16%
272
11th to 20thDay
4411%32%34%14%
270
21st to endDay
9%314%30%34%11%
270
December1st to 10thDay
15%29%40%24%10%
205
11th to 20thDay
14%416%33%21%13%
180
21st to endDay
22%416%31%20%8%
198
January1st to 10thNight
18%211%35%24%10%
760
11th to 20thNight
12%310%39%28%9%
732
21st to endNight
18%28%38%28%6%
792
February1st to 10thNight
15%210%37%26%10%
720
11th to 20thNight
12%314%34%29%7%
704
21st to endNight
17%212%44%21%4
592
March1st to 10thNight
16%315%38%23%4
720
11th to 20thNight
13%316%33%27%7%
720
21st to endNight
13%319%39%24%3
792
April1st to 10thNight
10%5%21%34%27%3
720
11th to 20thNight
7%7%24%36%21%5%
711
21st to endNight
6%5%25%34%24%6%
720
May1st to 10thNight
45%24%39%23%4
684
11th to 20thNight
5%324%45%22%1
496
21st to endNight
45%26%36%28%1
389
June1st to 10thNight
4424%47%18%3
360
11th to 20thNight
1421%51%23%
360
21st to endNight
119%50%29%1
360
July1st to 10thNight
12%51%35%1
350
11th to 20thNight
26%49%40%2
348
21st to endNight
117%33%51%8%
558
August1st to 10thNight
310%44%37%6%
628
11th to 20thNight
9%42%42%6%
712
21st to endNight
2437%49%7%
792
September1st to 10thNight
17%35%49%8%
720
11th to 20thNight
2111%40%37%9%
720
21st to endNight
2111%33%42%11%
720
October1st to 10thNight
4110%38%38%9%
720
11th to 20thNight
427%36%41%10%
720
21st to endNight
5%19%34%34%17%
792
November1st to 10thNight
10%28%32%35%13%
740
11th to 20thNight
6%19%43%32%9%
760
21st to endNight
9%110%38%33%9%
760
December1st to 10thNight
16%111%36%28%8%
760
11th to 20thNight
18%19%39%27%5%
760
21st to endNight
19%211%41%21%5%
836
Page generated at 2024-01-10 16:35:20. Version ac07

Copyright 2024 Attilla Danko


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