Lehman Caves Visitor Center
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lehman Caves Visitor Center clear sky chart from 2005-11-06 to 2024-03-06.

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
57%
23855
27%
79297
21%
23770
65%
23770
37%
41213

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%
750
28%
4001
17%
736
61%
736
25%
1763
January11th to 20thNight
53%
756
23%
4047
21%
740
62%
740
23%
1988
January21st to endNight
52%
827
18%
4342
22%
814
61%
814
22%
2207
February1st to 10thNight
48%
760
25%
2393
19%
760
58%
760
36%
1297
February11th to 20thNight
50%
740
26%
2219
20%
740
60%
740
37%
1248
February21st to endNight
47%
628
24%
1884
19%
628
57%
628
35%
1079
March1st to 10thNight
47%
742
22%
2200
16%
742
57%
742
31%
1308
March11th to 20thNight
51%
720
24%
1980
17%
720
58%
720
37%
1177
March21st to endNight
44%
792
25%
2178
12%
792
54%
792
36%
1264
April1st to 10thNight
47%
720
25%
1870
12%
720
55%
720
36%
1125
April11th to 20thNight
44%
653
28%
1721
12%
653
53%
653
39%
983
April21st to endNight
49%
540
30%
1620
15%
540
60%
540
40%
852
May1st to 10thNight
47%
540
25%
1620
14%
540
55%
540
34%
914
May11th to 20thNight
56%
531
27%
1595
22%
531
61%
531
41%
831
May21st to endNight
48%
582
20%
1746
14%
582
54%
582
31%
1002
June1st to 10thNight
57%
540
25%
1620
19%
540
65%
540
42%
824
June11th to 20thNight
54%
421
30%
1501
27%
421
66%
421
42%
672
June21st to endNight
71%
360
30%
1440
33%
360
82%
360
49%
573
July1st to 10thNight
74%
350
27%
1400
30%
350
80%
350
42%
631
July11th to 20thNight
65%
488
21%
1532
20%
488
67%
488
34%
844
July21st to endNight
66%
591
21%
1674
19%
558
67%
558
32%
987
August1st to 10thNight
66%
537
28%
1602
21%
534
70%
534
40%
864
August11th to 20thNight
74%
534
34%
1602
25%
534
77%
534
50%
767
August21st to endNight
75%
760
34%
1948
23%
760
77%
760
55%
1022
September1st to 10thNight
74%
720
34%
1907
23%
720
78%
720
57%
976
September11th to 20thNight
70%
720
37%
1980
26%
720
77%
720
54%
988
September21st to endNight
70%
720
40%
1980
29%
720
78%
720
63%
922
October1st to 10thNight
65%
720
34%
1980
22%
720
74%
720
50%
1034
October11th to 20thNight
69%
720
37%
2124
29%
720
77%
720
52%
1025
October21st to endNight
63%
792
38%
2489
29%
792
75%
792
51%
1149
November1st to 10thNight
65%
740
32%
2405
28%
740
73%
740
45%
1155
November11th to 20thNight
62%
760
34%
2470
28%
760
72%
760
49%
1140
November21st to endNight
55%
760
32%
2470
27%
760
66%
760
40%
1248
December1st to 10thNight
53%
760
25%
2470
19%
760
61%
760
36%
1319
December11th to 20thNight
49%
759
25%
2903
18%
758
58%
758
26%
1641
December21st to endNight
41%
822
15%
4384
15%
817
52%
817
18%
2394

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
24245%35%5%6%8%55%
79480
Night
24244345%6%8%58%
80107
TransparencyDay
25%8%10%19%23%15%
79200
Night
23%8%12%22%23%13%
79910
SeeingDay
5%15%30%29%16%4
14107
Night
48%25%36%22%5%
23899

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%46%5%46%7%9%12%44%
2858
11th to 20thDay
425%7%45%7%7%10%49%
2860
21st to endDay
37%36%5%345%5%9%50%
3146
February1st to 10thDay
15%36%4346%7%11%49%
1786
11th to 20thDay
26%25%5%35%5%7%9%50%
1850
21st to endDay
16%35%435%6%5%9%52%
1570
March1st to 10thDay
26%35%6%45%5%7%9%48%
1876
11th to 20thDay
26%36%5%345%6%10%49%
1980
21st to endDay
36%345%36%5%8%9%48%
2178
April1st to 10thDay
25%25%5%446%7%8%51%
2088
11th to 20thDay
36%245%45%5%6%8%53%
2185
21st to endDay
45%344345%6%8%54%
2340
May1st to 10thDay
45%146%46%6%6%6%52%
2340
11th to 20thDay
45%25%5%36%6%6%10%47%
2301
21st to endDay
5%6%246%36%7%6%8%47%
2530
June1st to 10thDay
13236%35%6%6%8%57%
2340
11th to 20thDay
3313424446%66%
2452
21st to endDay
221242445%6%67%
2520
July1st to 10thDay
4315%435%45%5%60%
2520
11th to 20thDay
34245%36%6%6%6%54%
2372
21st to endDay
5%4245%5%6%6%7%9%46%
2545
August1st to 10thDay
33135%35%5%5%7%59%
2328
11th to 20thDay
32245%3445%5%63%
2299
21st to endDay
33144445%6%7%61%
2405
September1st to 10thDay
3314433345%67%
2052
11th to 20thDay
1313323335%71%
1980
21st to endDay
233312335%73%
1980
October1st to 10thDay
4323425%45%6%61%
1980
11th to 20thDay
231322345%6%69%
1836
21st to endDay
232332445%6%67%
1864
November1st to 10thDay
241333446%10%60%
1674
11th to 20thDay
12133245%6%8%64%
1710
21st to endDay
2325%436%5%5%7%58%
1710
December1st to 10thDay
242443447%10%56%
1710
11th to 20thDay
28%47%6%35%5%8%9%43%
2169
21st to endDay
1437%7%47%7%8%11%42%
3146
January1st to 10thNight
424435%7%8%11%52%
4097
11th to 20thNight
1325%436%6%8%14%49%
4110
21st to endNight
27%35%43447%11%51%
4521
February1st to 10thNight
13245%345%6%10%56%
2393
11th to 20thNight
1435%436%5%7%9%53%
2218
21st to endNight
1435%435%5%6%9%53%
1884
March1st to 10thNight
26%345%35%6%6%9%52%
2200
11th to 20thNight
25%24435%5%8%10%52%
1980
21st to endNight
2424435%6%6%10%54%
2178
April1st to 10thNight
33235%36%6%6%8%54%
1870
11th to 20thNight
36%23335%5%6%8%57%
1721
21st to endNight
4313345%6%5%8%58%
1620
May1st to 10thNight
5%4245%35%6%5%7%54%
1620
11th to 20thNight
44135%345%6%9%57%
1594
21st to endNight
6%5%25%5%345%6%9%51%
1746
June1st to 10thNight
332243445%8%60%
1620
11th to 20thNight
2324423336%68%
1501
21st to endNight
221432336%7%67%
1440
July1st to 10thNight
22144345%6%6%64%
1440
11th to 20thNight
44246%36%5%6%6%53%
1583
21st to endNight
45%25%6%5%6%6%6%8%47%
1773
August1st to 10thNight
3325%345%6%6%6%57%
1611
11th to 20thNight
231343435%6%65%
1602
21st to endNight
321342445%6%66%
1948
September1st to 10thNight
331342345%469%
1907
11th to 20thNight
231332435%6%69%
1980
21st to endNight
2211222235%77%
1980
October1st to 10thNight
5%313323345%67%
1980
11th to 20thNight
3312324435%71%
2124
21st to endNight
131322345%6%69%
2489
November1st to 10thNight
142222347%8%65%
2405
11th to 20thNight
221332335%8%68%
2470
21st to endNight
2414425%5%6%10%57%
2470
December1st to 10thNight
2424435%5%5%9%58%
2470
11th to 20thNight
1435%5%36%5%8%12%48%
3041
21st to endNight
15%37%7%45%6%8%9%45%
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
27%12%18%29%13%1
2859
11th to 20thDay
30%11%19%22%14%4
2860
21st to endDay
31%9%19%23%16%3
3146
February1st to 10thDay
28%10%15%25%15%7%
1786
11th to 20thDay
28%8%14%21%22%6%
1860
21st to endDay
27%9%14%24%22%4
1570
March1st to 10thDay
31%10%11%26%18%4
1876
11th to 20thDay
30%8%11%30%14%7%
1980
21st to endDay
29%10%14%26%17%3
2178
April1st to 10thDay
28%9%12%23%18%9%
2088
11th to 20thDay
27%8%10%24%24%8%
2188
21st to endDay
26%8%9%25%27%5%
2340
May1st to 10thDay
28%7%10%20%29%7%
2340
11th to 20thDay
28%9%9%18%28%7%
2304
21st to endDay
30%10%10%18%25%7%
2530
June1st to 10thDay
21%7%9%15%33%16%
2340
11th to 20thDay
18%6%5%13%29%29%
2452
21st to endDay
15%5%6%11%25%39%
2520
July1st to 10thDay
24%6%5%7%17%41%
2451
11th to 20thDay
25%7%8%11%18%31%
2301
21st to endDay
30%10%10%12%15%24%
2404
August1st to 10thDay
22%6%9%9%20%34%
2313
11th to 20thDay
20%6%7%9%21%37%
2299
21st to endDay
20%6%6%12%28%27%
2405
September1st to 10thDay
19%5%5%10%27%35%
2052
11th to 20thDay
15%5%5%16%28%30%
1980
21st to endDay
15%45%16%33%27%
1980
October1st to 10thDay
22%6%9%14%34%15%
1980
11th to 20thDay
15%47%21%37%15%
1836
21st to endDay
19%46%29%32%10%
1864
November1st to 10thDay
20%6%13%24%27%10%
1674
11th to 20thDay
16%9%10%33%27%6%
1710
21st to endDay
25%8%10%23%25%9%
1710
December1st to 10thDay
24%10%14%28%19%6%
1710
11th to 20thDay
36%10%14%19%15%6%
2168
21st to endDay
31%11%14%19%19%5%
3146
January1st to 10thNight
22%9%18%29%19%2
4097
11th to 20thNight
25%11%22%25%12%4
4110
21st to endNight
29%8%19%23%17%4
4521
February1st to 10thNight
24%9%16%28%17%6%
2393
11th to 20thNight
27%7%13%20%23%9%
2219
21st to endNight
26%9%15%21%22%6%
1884
March1st to 10thNight
29%9%13%25%19%4
2200
11th to 20thNight
27%9%11%29%18%6%
1980
21st to endNight
24%10%15%28%19%4
2178
April1st to 10thNight
25%10%11%26%19%9%
1870
11th to 20thNight
23%8%11%25%28%6%
1721
21st to endNight
21%7%12%25%28%6%
1620
May1st to 10thNight
27%8%8%23%28%6%
1620
11th to 20thNight
23%7%10%23%28%9%
1595
21st to endNight
29%8%12%20%26%5%
1746
June1st to 10thNight
20%7%9%16%33%15%
1620
11th to 20thNight
19%45%12%28%31%
1501
21st to endNight
15%5%6%11%25%39%
1440
July1st to 10thNight
20%6%5%9%18%42%
1400
11th to 20thNight
27%8%7%13%14%30%
1532
21st to endNight
32%8%10%14%15%21%
1674
August1st to 10thNight
24%7%8%11%16%33%
1602
11th to 20thNight
18%6%6%12%22%35%
1602
21st to endNight
18%5%7%13%24%33%
1948
September1st to 10thNight
17%47%13%26%33%
1907
11th to 20thNight
16%5%8%15%25%31%
1980
21st to endNight
12%46%15%35%27%
1980
October1st to 10thNight
19%5%8%16%36%16%
1980
11th to 20thNight
16%6%6%17%40%15%
2124
21st to endNight
16%6%7%29%32%11%
2489
November1st to 10thNight
18%7%11%29%24%11%
2405
11th to 20thNight
15%7%11%30%29%8%
2470
21st to endNight
22%7%9%27%28%8%
2470
December1st to 10thNight
24%9%15%27%18%7%
2470
11th to 20thNight
29%10%12%25%17%7%
3041
21st to endNight
32%10%11%20%20%6%
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
6%18%31%29%14%1
270
11th to 20thDay
416%34%25%16%4
270
21st to endDay
212%29%30%20%7%
297
February1st to 10thDay
5%20%34%21%17%2
346
11th to 20thDay
6%20%36%24%13%1
455
21st to endDay
420%40%26%10%1
382
March1st to 10thDay
6%24%33%24%11%2
441
11th to 20thDay
6%21%34%24%11%4
420
21st to endDay
10%22%38%23%7%1
462
April1st to 10thDay
9%24%29%26%9%4
420
11th to 20thDay
8%27%35%21%7%2
412
21st to endDay
9%28%28%22%10%3
420
May1st to 10thDay
9%23%35%24%9%1
423
11th to 20thDay
8%17%30%29%13%4
448
21st to endDay
8%17%29%26%16%4
485
June1st to 10thDay
414%32%29%17%4
450
11th to 20thDay
6%17%31%29%15%2
450
21st to endDay
211%32%34%19%2
450
July1st to 10thDay
4428%41%20%3
446
11th to 20thDay
45%27%39%20%6%
444
21st to endDay
4422%40%23%7%
487
August1st to 10thDay
45%30%37%19%5%
447
11th to 20thDay
35%25%37%24%7%
437
21st to endDay
37%25%37%21%6%
495
September1st to 10thDay
49%27%30%20%10%
450
11th to 20thDay
412%30%26%21%7%
450
21st to endDay
412%25%32%21%6%
450
October1st to 10thDay
6%16%28%26%16%8%
450
11th to 20thDay
313%25%29%21%9%
306
21st to endDay
7%10%26%33%19%5%
297
November1st to 10thDay
9%14%25%24%20%9%
270
11th to 20thDay
213%31%30%17%6%
270
21st to endDay
412%27%29%21%8%
270
December1st to 10thDay
5%12%30%32%15%6%
270
11th to 20thDay
413%32%34%14%3
270
21st to endDay
7%17%27%35%10%3
297
January1st to 10thNight
49%30%31%18%8%
760
11th to 20thNight
210%27%34%22%5%
760
21st to endNight
5%9%28%34%17%7%
836
February1st to 10thNight
49%32%35%15%5%
760
11th to 20thNight
5%9%32%36%15%3
744
21st to endNight
411%31%38%14%2
628
March1st to 10thNight
5%13%30%34%15%3
742
11th to 20thNight
410%27%35%20%4
720
21st to endNight
313%34%34%13%2
792
April1st to 10thNight
6%14%28%34%15%3
720
11th to 20thNight
6%15%33%30%15%2
653
21st to endNight
6%11%30%32%18%3
540
May1st to 10thNight
9%9%31%36%15%1
540
11th to 20thNight
5%7%24%37%23%4
531
21st to endNight
9%11%25%31%22%3
584
June1st to 10thNight
5%10%22%37%22%4
540
11th to 20thNight
410%27%37%20%2
421
21st to endNight
1321%46%27%3
360
July1st to 10thNight
115%45%35%4
350
11th to 20thNight
6%318%42%27%4
488
21st to endNight
6%215%41%34%3
591
August1st to 10thNight
4219%49%25%1
537
11th to 20thNight
4216%43%33%3
534
21st to endNight
4214%40%34%7%
760
September1st to 10thNight
3413%38%33%10%
720
11th to 20thNight
35%16%35%32%9%
720
21st to endNight
25%18%28%34%12%
720
October1st to 10thNight
6%7%19%37%24%7%
720
11th to 20thNight
45%17%36%29%9%
720
21st to endNight
36%24%32%26%9%
792
November1st to 10thNight
49%19%35%25%8%
740
11th to 20thNight
37%26%37%21%8%
760
21st to endNight
48%27%28%24%8%
760
December1st to 10thNight
47%30%35%18%6%
760
11th to 20thNight
47%32%35%18%3
760
21st to endNight
411%35%36%13%3
836
Page generated at 2024-03-03 03:28:54. Version ac07

Copyright © 2024 Attilla Danko.


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