Wilkerson Pass
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Wilkerson Pass 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
50%
24507
28%
74439
17%
24459
61%
24459
42%
38839

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
43%
948
33%
2647
14%
946
60%
946
52%
1301
January11th to 20thNight
38%
821
35%
2459
18%
821
56%
821
51%
1157
January21st to endNight
45%
792
34%
2574
21%
792
62%
792
46%
1239
February1st to 10thNight
37%
720
31%
2340
14%
720
58%
720
48%
1094
February11th to 20thNight
35%
702
29%
2130
11%
700
54%
700
44%
1079
February21st to endNight
36%
592
38%
1776
14%
592
60%
592
47%
891
March1st to 10thNight
39%
720
30%
2147
13%
720
55%
720
48%
1077
March11th to 20thNight
49%
720
28%
1980
15%
720
58%
720
45%
1107
March21st to endNight
38%
680
29%
2066
11%
680
56%
680
38%
1125
April1st to 10thNight
39%
540
28%
1800
15%
540
56%
540
41%
871
April11th to 20thNight
36%
533
24%
1777
14%
533
50%
533
31%
996
April21st to endNight
41%
540
24%
1800
16%
540
56%
540
32%
1007
May1st to 10thNight
44%
540
21%
1740
16%
540
52%
540
30%
994
May11th to 20thNight
52%
531
15%
1418
12%
531
54%
531
31%
923
May21st to endNight
50%
583
19%
1552
11%
582
59%
582
38%
920
June1st to 10thNight
64%
540
22%
1440
16%
540
69%
540
47%
783
June11th to 20thNight
62%
540
26%
1440
19%
540
65%
540
52%
748
June21st to endNight
70%
540
24%
1440
20%
540
72%
540
45%
797
July1st to 10thNight
69%
525
17%
1400
17%
525
70%
525
34%
878
July11th to 20thNight
74%
522
24%
1392
21%
522
75%
522
42%
795
July21st to endNight
71%
591
13%
1598
13%
558
72%
558
29%
1009
August1st to 10thNight
68%
537
14%
1602
13%
534
69%
534
30%
972
August11th to 20thNight
73%
534
24%
1769
25%
534
75%
534
36%
969
August21st to endNight
70%
594
24%
1980
27%
594
72%
594
33%
1108
September1st to 10thNight
67%
540
27%
1800
27%
540
73%
540
35%
974
September11th to 20thNight
67%
540
33%
1800
29%
540
75%
540
41%
908
September21st to endNight
57%
550
30%
1990
25%
550
67%
550
40%
962
October1st to 10thNight
54%
720
29%
2160
15%
720
64%
720
41%
1171
October11th to 20thNight
57%
720
38%
2160
19%
720
71%
720
59%
977
October21st to endNight
53%
796
37%
2380
19%
796
65%
796
47%
1201
November1st to 10thNight
50%
925
35%
2405
16%
925
60%
925
58%
1211
November11th to 20thNight
46%
950
38%
2470
17%
950
59%
950
56%
1235
November21st to endNight
50%
950
33%
2562
16%
950
61%
950
51%
1303
December1st to 10thNight
41%
950
30%
2660
14%
950
54%
950
51%
1311
December11th to 20thNight
40%
948
29%
3116
14%
948
53%
948
43%
1541
December21st to endNight
33%
1033
20%
4669
12%
1026
49%
1026
28%
2205

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
45%25%5%35%5%6%8%52%
74763
Night
342442445%8%59%
74988
TransparencyDay
28%6%11%25%23%8%
74474
Night
23%6%13%28%24%7%
74799
SeeingDay
7%11%27%31%18%5%
14352
Night
46%33%41%15%1
24526

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
31432345%8%66%
1518
11th to 20thDay
1426%42335%9%62%
1560
21st to endDay
5%36%42445%8%58%
1782
February1st to 10thDay
427%43345%9%60%
1620
11th to 20thDay
21432446%8%64%
1717
21st to endDay
435%5%3345%8%61%
1480
March1st to 10thDay
2425%42446%8%59%
1809
11th to 20thDay
38%3444446%9%52%
1980
21st to endDay
26%35%425%5%6%9%52%
2290
April1st to 10thDay
35%33435%5%7%9%53%
2160
11th to 20thDay
49%36%445%5%5%7%47%
2131
21st to endDay
49%35%6%45%5%7%7%45%
2160
May1st to 10thDay
7%8%36%5%35%6%7%10%40%
2218
11th to 20thDay
7%8%36%7%46%6%7%8%38%
2473
21st to endDay
6%6%25%5%35%6%7%9%45%
2724
June1st to 10thDay
4424435%7%8%11%47%
2520
11th to 20thDay
5%424435%5%6%8%54%
2520
21st to endDay
44245%47%7%7%8%48%
2520
July1st to 10thDay
7%425%6%47%7%8%9%42%
2520
11th to 20thDay
7%425%5%46%6%7%9%44%
2520
21st to endDay
10%5%47%7%47%7%7%9%33%
2623
August1st to 10thDay
10%6%37%8%5%5%6%6%9%36%
2328
11th to 20thDay
7%425%6%36%6%6%9%47%
2132
21st to endDay
7%5%16%6%36%6%6%8%46%
2376
September1st to 10thDay
7%336%5%35%5%6%7%50%
2160
11th to 20thDay
6%4245%2445%7%57%
2159
21st to endDay
6%324423347%63%
1967
October1st to 10thDay
5%4245%3445%7%57%
1800
11th to 20thDay
3422333347%68%
1800
21st to endDay
35%24433346%62%
1958
November1st to 10thDay
122331235%6%71%
1673
11th to 20thDay
141332235%8%69%
1710
21st to endDay
425%42435%9%62%
1615
December1st to 10thDay
132442445%9%62%
1520
11th to 20thDay
13243235%6%11%60%
1926
21st to endDay
1326%5%3446%9%57%
2794
January1st to 10thNight
31432335%7%68%
2647
11th to 20thNight
1313423347%69%
2459
21st to endNight
1324423346%65%
2574
February1st to 10thNight
425%413348%66%
2340
11th to 20thNight
15%25%424448%62%
2130
21st to endNight
5%25%32335%7%64%
1776
March1st to 10thNight
1424323449%62%
2147
11th to 20thNight
36%3442445%8%57%
1980
21st to endNight
26%35%42435%7%58%
2066
April1st to 10thNight
26%24423347%63%
1800
11th to 20thNight
48%36%5%24348%53%
1777
21st to endNight
5%9%35%43345%7%54%
1800
May1st to 10thNight
6%8%45%44445%8%49%
1740
11th to 20thNight
6%9%36%5%345%6%8%44%
1417
21st to endNight
7%6%334245%6%8%52%
1552
June1st to 10thNight
44133245%6%10%59%
1440
11th to 20thNight
42124235%6%9%62%
1440
21st to endNight
3413435%5%8%9%55%
1440
July1st to 10thNight
5%5%345%45%7%7%11%45%
1440
11th to 20thNight
3325%6%45%5%6%9%53%
1440
21st to endNight
6%426%6%37%8%7%13%38%
1692
August1st to 10thNight
7%5%25%5%36%6%8%9%46%
1611
11th to 20thNight
6%4145%45%5%6%8%51%
1769
21st to endNight
6%5%245%35%6%6%10%49%
1980
September1st to 10thNight
6%425%5%345%7%10%51%
1800
11th to 20thNight
7%413324447%59%
1800
21st to endNight
6%424423446%61%
1990
October1st to 10thNight
6%32443345%6%60%
2160
11th to 20thNight
2312223345%74%
2160
21st to endNight
35%2442345%6%63%
2380
November1st to 10thNight
1213323336%71%
2405
11th to 20thNight
323313347%70%
2470
21st to endNight
25%24223348%65%
2562
December1st to 10thNight
122432345%9%65%
2660
11th to 20thNight
13243246%6%9%61%
3271
21st to endNight
1435%5%2445%9%57%
4873

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
17%416%34%23%5%
1519
11th to 20thDay
21%5%15%29%25%5%
1560
21st to endDay
23%5%11%33%21%6%
1782
February1st to 10thDay
22%5%16%30%19%8%
1620
11th to 20thDay
18%5%11%28%31%7%
1727
21st to endDay
23%49%24%28%12%
1480
March1st to 10thDay
22%5%9%30%28%6%
1809
11th to 20thDay
29%5%9%29%23%5%
1980
21st to endDay
28%6%10%30%20%6%
2290
April1st to 10thDay
26%5%12%26%20%10%
2160
11th to 20thDay
34%6%8%25%21%6%
2134
21st to endDay
35%7%8%28%19%3
2160
May1st to 10thDay
38%7%11%22%19%3
2218
11th to 20thDay
41%7%14%23%13%2
2477
21st to endDay
33%7%13%22%18%8%
2724
June1st to 10thDay
29%7%15%20%21%9%
2520
11th to 20thDay
27%6%8%19%23%18%
2520
21st to endDay
28%8%10%22%21%11%
2520
July1st to 10thDay
34%9%10%18%19%10%
2451
11th to 20thDay
34%8%13%22%16%7%
2445
21st to endDay
44%10%18%17%10%2
2477
August1st to 10thDay
43%8%14%14%14%6%
2313
11th to 20thDay
31%8%12%20%20%9%
2132
21st to endDay
33%7%10%23%21%6%
2376
September1st to 10thDay
31%6%8%18%24%13%
2160
11th to 20thDay
27%5%9%19%27%13%
2159
21st to endDay
23%46%24%34%9%
1967
October1st to 10thDay
25%6%7%23%28%11%
1800
11th to 20thDay
17%45%24%37%13%
1800
21st to endDay
23%47%27%29%10%
1958
November1st to 10thDay
14%410%25%34%13%
1673
11th to 20thDay
15%5%6%36%29%8%
1710
21st to endDay
20%49%27%29%11%
1615
December1st to 10thDay
19%6%15%30%25%6%
1520
11th to 20thDay
18%6%14%34%25%4
1924
21st to endDay
20%9%9%27%25%9%
2794
January1st to 10thNight
17%414%34%26%5%
2647
11th to 20thNight
15%5%15%30%30%6%
2459
21st to endNight
19%5%10%32%27%6%
2574
February1st to 10thNight
19%413%36%22%6%
2340
11th to 20thNight
22%411%30%27%6%
2130
21st to endNight
21%47%30%29%9%
1776
March1st to 10thNight
20%5%9%31%31%5%
2147
11th to 20thNight
25%5%9%33%23%4
1980
21st to endNight
26%7%11%29%24%3
2066
April1st to 10thNight
21%5%12%31%25%6%
1800
11th to 20thNight
32%5%9%29%21%4
1777
21st to endNight
32%5%13%29%19%3
1800
May1st to 10thNight
34%5%12%29%16%4
1740
11th to 20thNight
37%7%18%22%14%2
1418
21st to endNight
29%6%17%23%19%6%
1552
June1st to 10thNight
22%6%23%25%14%10%
1440
11th to 20thNight
19%6%13%23%22%17%
1440
21st to endNight
22%7%13%25%21%11%
1440
July1st to 10thNight
32%9%16%19%16%7%
1400
11th to 20thNight
26%7%17%28%16%6%
1392
21st to endNight
33%11%27%20%7%1
1598
August1st to 10thNight
32%11%22%19%12%4
1602
11th to 20thNight
30%5%17%25%18%5%
1769
21st to endNight
30%7%15%28%16%4
1980
September1st to 10thNight
28%7%12%23%21%9%
1800
11th to 20thNight
23%6%13%22%23%13%
1800
21st to endNight
24%49%27%29%6%
1990
October1st to 10thNight
25%6%10%23%26%10%
2160
11th to 20thNight
14%48%24%37%13%
2160
21st to endNight
20%5%8%30%29%8%
2380
November1st to 10thNight
15%410%27%32%11%
2405
11th to 20thNight
14%5%8%36%29%9%
2470
21st to endNight
19%39%29%28%11%
2562
December1st to 10thNight
17%5%17%30%25%7%
2660
11th to 20thNight
18%6%14%29%28%4
3272
21st to endNight
23%7%11%25%28%6%
4873

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
414%28%35%15%4
270
11th to 20thDay
6%12%35%38%9%1
246
21st to endDay
26%41%42%8%1
264
February1st to 10thDay
25%40%30%41
240
11th to 20thDay
123%38%31%5%2
240
21st to endDay
5%22%40%27%5%1
198
March1st to 10thDay
219%35%32%12%
249
11th to 20thDay
8%15%36%30%11%
420
21st to endDay
8%22%39%25%6%
462
April1st to 10thDay
8%20%31%31%9%1
420
11th to 20thDay
12%28%30%21%8%1
412
21st to endDay
11%17%37%25%8%2
420
May1st to 10thDay
9%14%36%28%11%2
481
11th to 20thDay
9%12%22%36%17%4
625
21st to endDay
8%12%25%30%21%4
679
June1st to 10thDay
5%10%21%32%25%6%
630
11th to 20thDay
7%8%27%35%19%4
630
21st to endDay
45%28%32%25%6%
630
July1st to 10thDay
8%213%34%34%8%
621
11th to 20thDay
8%113%31%36%11%
618
21st to endDay
12%218%25%32%11%
565
August1st to 10thDay
12%221%31%25%9%
447
11th to 20thDay
9%5%23%28%26%10%
437
21st to endDay
11%5%21%32%23%9%
495
September1st to 10thDay
9%6%21%32%26%7%
450
11th to 20thDay
7%8%30%31%18%6%
449
21st to endDay
7%10%20%26%24%13%
270
October1st to 10thDay
6%14%26%20%22%13%
270
11th to 20thDay
7%14%23%28%22%4
270
21st to endDay
7%14%30%30%16%3
297
November1st to 10thDay
7%13%30%31%14%6%
270
11th to 20thDay
414%28%39%12%3
270
21st to endDay
410%36%36%12%1
270
December1st to 10thDay
8%11%35%33%10%3
270
11th to 20thDay
413%37%37%8%1
270
21st to endDay
7%18%32%32%8%3
297
January1st to 10thNight
18%42%39%9%2
950
11th to 20thNight
29%45%35%8%1
821
21st to endNight
2442%45%7%
792
February1st to 10thNight
15%50%38%6%
720
11th to 20thNight
27%50%35%6%
704
21st to endNight
35%51%38%4
592
March1st to 10thNight
26%47%38%7%
720
11th to 20thNight
4438%46%8%
720
21st to endNight
48%43%40%4
680
April1st to 10thNight
311%41%41%3
540
11th to 20thNight
8%10%41%35%6%1
533
21st to endNight
8%8%36%39%8%
540
May1st to 10thNight
8%6%34%41%10%1
540
11th to 20thNight
9%424%45%16%1
531
21st to endNight
10%6%25%41%16%2
584
June1st to 10thNight
5%421%44%24%2
540
11th to 20thNight
4327%51%13%2
540
21st to endNight
4118%49%26%2
540
July1st to 10thNight
7%110%42%38%3
525
11th to 20thNight
4210%37%44%4
522
21st to endNight
7%16%36%47%3
591
August1st to 10thNight
9%110%38%39%2
537
11th to 20thNight
6%211%46%33%2
534
21st to endNight
7%11%43%36%2
594
September1st to 10thNight
6%114%45%29%4
540
11th to 20thNight
8%116%48%25%3
540
21st to endNight
7%425%43%19%2
550
October1st to 10thNight
6%5%29%43%15%3
720
11th to 20thNight
2434%46%13%1
720
21st to endNight
46%32%43%13%2
796
November1st to 10thNight
26%37%42%11%1
925
11th to 20thNight
28%40%41%8%1
950
21st to endNight
49%33%46%8%
950
December1st to 10thNight
29%41%40%7%
950
11th to 20thNight
28%43%39%7%
950
21st to endNight
211%42%37%7%1
1045
Page generated at 2024-01-09 23:25:02. Version ac07

Copyright 2024 Attilla Danko


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