Wildflower Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Wildflower Observatory 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
76%
24156
37%
74372
33%
24111
81%
24111
55%
34730

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
73%
758
33%
2457
34%
756
78%
756
45%
1205
January11th to 20thNight
72%
728
38%
2366
37%
728
78%
728
49%
1130
January21st to endNight
64%
792
38%
2574
33%
792
74%
792
44%
1283
February1st to 10thNight
72%
720
39%
2222
37%
720
79%
720
54%
1029
February11th to 20thNight
67%
700
36%
2099
33%
700
75%
700
47%
1069
February21st to endNight
64%
592
36%
1776
34%
592
72%
592
48%
886
March1st to 10thNight
64%
720
38%
1994
29%
720
74%
720
55%
992
March11th to 20thNight
71%
720
39%
1980
32%
720
77%
720
57%
984
March21st to endNight
70%
792
40%
2178
28%
792
78%
792
58%
1041
April1st to 10thNight
71%
720
36%
1980
24%
720
79%
720
61%
933
April11th to 20thNight
66%
641
40%
1862
27%
641
76%
641
63%
811
April21st to endNight
69%
540
48%
1620
36%
540
79%
540
71%
649
May1st to 10thNight
70%
540
43%
1620
32%
540
78%
540
65%
679
May11th to 20thNight
73%
531
42%
1594
33%
531
78%
531
69%
658
May21st to endNight
77%
582
41%
1746
32%
582
82%
582
75%
685
June1st to 10thNight
82%
540
37%
1620
31%
540
84%
540
72%
657
June11th to 20thNight
85%
540
41%
1620
34%
540
88%
540
86%
594
June21st to endNight
86%
540
34%
1620
29%
540
87%
540
69%
684
July1st to 10thNight
83%
525
29%
1575
24%
525
84%
525
56%
760
July11th to 20thNight
84%
522
30%
1566
25%
522
84%
522
47%
818
July21st to endNight
80%
591
27%
1674
21%
558
82%
558
39%
937
August1st to 10thNight
86%
537
32%
1602
28%
534
86%
534
52%
802
August11th to 20thNight
87%
534
35%
1602
31%
534
88%
534
47%
811
August21st to endNight
84%
757
34%
2034
28%
757
84%
757
54%
1065
September1st to 10thNight
81%
720
33%
1980
30%
720
82%
720
51%
1042
September11th to 20thNight
85%
720
43%
1980
37%
720
87%
720
69%
890
September21st to endNight
83%
720
41%
1980
34%
720
87%
720
64%
924
October1st to 10thNight
79%
720
42%
1983
33%
720
83%
720
64%
927
October11th to 20thNight
85%
720
46%
2160
41%
720
89%
720
77%
855
October21st to endNight
81%
792
47%
2376
40%
792
88%
792
73%
941
November1st to 10thNight
81%
740
44%
2220
41%
740
85%
740
64%
979
November11th to 20thNight
83%
760
41%
2467
42%
760
87%
760
63%
1011
November21st to endNight
72%
760
40%
2470
38%
760
79%
760
51%
1130
December1st to 10thNight
75%
760
39%
2470
39%
760
79%
760
50%
1145
December11th to 20thNight
71%
759
34%
2945
36%
758
76%
758
34%
1566
December21st to endNight
68%
823
24%
4360
36%
817
73%
817
26%
2158

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
3213323346%71%
74933
Night
4213323346%69%
74835
TransparencyDay
16%3411%24%41%
74660
Night
17%3311%22%43%
74630
SeeingDay
45%17%33%30%10%
13922
Night
4212%43%35%3
24178

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
5%323422245%66%
1708
11th to 20thDay
4324223345%67%
1638
21st to endDay
6%314423346%64%
1782
February1st to 10thDay
331332335%5%70%
1735
11th to 20thDay
6%324323346%64%
1750
21st to endDay
5%312323346%68%
1480
March1st to 10thDay
4323324446%65%
1964
11th to 20thDay
4213322346%68%
1980
21st to endDay
3212323335%72%
2178
April1st to 10thDay
2112223348%72%
1980
11th to 20thDay
2112212335%79%
2039
21st to endDay
1111212235%81%
2340
May1st to 10thDay
1111112235%82%
2340
11th to 20thDay
1111212235%80%
2301
21st to endDay
21111112387%
2530
June1st to 10thDay
1111112125%83%
2340
11th to 20thDay
11111112389%
2340
21st to endDay
111111223482%
2340
July1st to 10thDay
221232345%6%70%
2340
11th to 20thDay
32136%25%5%7%10%56%
2340
21st to endDay
5%3245%35%6%7%10%48%
2545
August1st to 10thDay
422342345%7%63%
2328
11th to 20thDay
32134245%7%9%61%
2299
21st to endDay
321343345%8%65%
2316
September1st to 10thDay
5%213423346%68%
1980
11th to 20thDay
311212222480%
1980
21st to endDay
311222233377%
1980
October1st to 10thDay
3112213345%75%
1976
11th to 20thDay
21111133385%
1800
21st to endDay
111221233481%
1980
November1st to 10thDay
122212335%79%
1859
11th to 20thDay
1213223335%76%
1710
21st to endDay
5%313323346%67%
1710
December1st to 10thDay
6%41442445%5%60%
1710
11th to 20thDay
4326%5%345%7%8%54%
2169
21st to endDay
9%6%25%42345%7%52%
3146
January1st to 10thNight
5%31442445%7%61%
2457
11th to 20thNight
6%213423335%68%
2366
21st to endNight
8%324334335%63%
2574
February1st to 10thNight
4313323345%70%
2222
11th to 20thNight
6%323324346%64%
2098
21st to endNight
6%213423335%67%
1776
March1st to 10thNight
431332345%7%65%
1994
11th to 20thNight
5%313223335%70%
1980
21st to endNight
4212223347%70%
2178
April1st to 10thNight
222221345%6%72%
1980
11th to 20thNight
221221223478%
1862
21st to endNight
212211225%82%
1620
May1st to 10thNight
1112222335%78%
1620
11th to 20thNight
111222223481%
1594
21st to endNight
21111211288%
1746
June1st to 10thNight
211113235%80%
1620
11th to 20thNight
1111122388%
1620
21st to endNight
2112212335%79%
1620
July1st to 10thNight
221332445%9%65%
1620
11th to 20thNight
22144345%8%11%57%
1620
21st to endNight
43135%46%7%9%11%47%
1773
August1st to 10thNight
11124346%7%8%61%
1611
11th to 20thNight
22134445%7%9%60%
1602
21st to endNight
32134246%6%8%62%
2034
September1st to 10thNight
43134245%6%7%62%
1980
11th to 20thNight
211222323379%
1980
21st to endNight
211232233478%
1980
October1st to 10thNight
311322334475%
1983
11th to 20thNight
111111123484%
2160
21st to endNight
1111212225%82%
2376
November1st to 10thNight
2212212345%75%
2220
11th to 20thNight
2212212335%77%
2467
21st to endNight
5%313323346%68%
2470
December1st to 10thNight
6%213322447%66%
2470
11th to 20thNight
6%425%5%3445%7%55%
3041
21st to endNight
8%5%245%44445%55%
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
22%3418%31%22%
1709
11th to 20thDay
22%3312%30%29%
1638
21st to endDay
23%3415%28%28%
1782
February1st to 10thDay
18%2415%25%36%
1735
11th to 20thDay
23%3414%26%30%
1760
21st to endDay
20%2313%31%31%
1480
March1st to 10thDay
21%3311%28%35%
1964
11th to 20thDay
18%2312%27%38%
1980
21st to endDay
17%229%33%36%
2178
April1st to 10thDay
12%228%36%40%
1980
11th to 20thDay
11%227%25%53%
2042
21st to endDay
9%227%24%57%
2340
May1st to 10thDay
8%237%24%57%
2340
11th to 20thDay
10%227%21%58%
2304
21st to endDay
7%11423%65%
2530
June1st to 10thDay
8%11319%68%
2340
11th to 20thDay
5%1129%82%
2340
21st to endDay
9%225%12%70%
2340
July1st to 10thDay
15%5%49%17%49%
2276
11th to 20thDay
21%7%11%20%25%17%
2271
21st to endDay
28%7%11%22%19%14%
2404
August1st to 10thDay
20%5%7%16%19%34%
2313
11th to 20thDay
19%7%8%18%24%25%
2299
21st to endDay
17%6%7%15%29%27%
2316
September1st to 10thDay
18%35%12%25%36%
1980
11th to 20thDay
11%235%28%51%
1980
21st to endDay
13%336%21%54%
1980
October1st to 10thDay
13%3412%24%45%
1976
11th to 20thDay
7%227%24%59%
1800
21st to endDay
10%239%27%49%
1980
November1st to 10thDay
10%2214%31%41%
1859
11th to 20thDay
14%2211%27%43%
1710
21st to endDay
20%2311%28%37%
1710
December1st to 10thDay
26%4414%24%29%
1710
11th to 20thDay
27%45%20%25%19%
2168
21st to endDay
31%5%6%21%24%13%
3146
January1st to 10thNight
23%4414%28%27%
2457
11th to 20thNight
21%3311%29%33%
2366
21st to endNight
25%2314%24%31%
2574
February1st to 10thNight
19%2311%24%41%
2222
11th to 20thNight
24%3412%24%34%
2099
21st to endNight
22%339%26%38%
1776
March1st to 10thNight
17%4211%25%40%
1994
11th to 20thNight
17%329%23%45%
1980
21st to endNight
16%239%31%39%
2178
April1st to 10thNight
14%238%26%47%
1980
11th to 20thNight
11%226%23%55%
1862
21st to endNight
9%125%21%61%
1620
May1st to 10thNight
11%226%22%56%
1620
11th to 20thNight
9%325%19%62%
1595
21st to endNight
8%11416%70%
1746
June1st to 10thNight
9%21314%71%
1620
11th to 20thNight
412211%80%
1620
21st to endNight
11%2249%72%
1620
July1st to 10thNight
16%5%6%9%16%48%
1575
11th to 20thNight
19%8%8%19%24%21%
1566
21st to endNight
26%8%11%21%18%17%
1674
August1st to 10thNight
18%6%5%19%18%34%
1602
11th to 20thNight
20%7%8%17%21%27%
1602
21st to endNight
19%47%14%24%30%
2034
September1st to 10thNight
21%5%6%14%19%35%
1980
11th to 20thNight
11%239%20%55%
1980
21st to endNight
13%326%18%58%
1980
October1st to 10thNight
14%3411%19%50%
1983
11th to 20thNight
7%128%20%62%
2160
21st to endNight
9%128%20%59%
2376
November1st to 10thNight
13%228%28%47%
2220
11th to 20thNight
12%2210%25%48%
2467
21st to endNight
20%3310%25%40%
2470
December1st to 10thNight
20%3417%22%35%
2470
11th to 20thNight
29%4412%26%24%
3041
21st to endNight
31%4418%25%19%
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
9%422%44%20%1
270
11th to 20thDay
10%5%16%38%27%4
246
21st to endDay
5%6%23%33%25%7%
264
February1st to 10thDay
46%22%32%27%8%
355
11th to 20thDay
11%10%25%34%18%2
415
21st to endDay
10%11%31%32%14%1
346
March1st to 10thDay
5%12%28%35%16%4
420
11th to 20thDay
7%8%23%33%22%7%
420
21st to endDay
5%14%27%35%17%2
462
April1st to 10thDay
411%23%32%23%7%
420
11th to 20thDay
313%30%28%21%4
412
21st to endDay
411%24%32%20%10%
420
May1st to 10thDay
39%26%31%24%7%
423
11th to 20thDay
27%23%34%27%7%
448
21st to endDay
28%21%35%27%7%
485
June1st to 10thDay
2320%33%31%11%
450
11th to 20thDay
1319%32%31%14%
450
21st to endDay
1212%40%36%10%
450
July1st to 10thDay
19%34%38%18%
446
11th to 20thDay
32430%40%22%
444
21st to endDay
415%27%39%24%
487
August1st to 10thDay
35%29%43%19%
447
11th to 20thDay
215%27%43%21%
437
21st to endDay
115%21%48%24%
495
September1st to 10thDay
428%31%42%14%
450
11th to 20thDay
3112%34%37%13%
450
21st to endDay
3417%30%32%14%
450
October1st to 10thDay
3419%32%35%8%
446
11th to 20thDay
4312%36%35%11%
270
21st to endDay
15%15%33%35%11%
297
November1st to 10thDay
2416%40%33%6%
270
11th to 20thDay
3312%43%32%7%
270
21st to endDay
46%20%37%27%5%
270
December1st to 10thDay
9%312%46%26%4
270
11th to 20thDay
2419%48%24%3
270
21st to endDay
11%6%22%35%22%3
297
January1st to 10thNight
5%113%49%28%3
760
11th to 20thNight
6%212%47%30%3
728
21st to endNight
9%317%44%24%3
792
February1st to 10thNight
5%314%47%26%4
720
11th to 20thNight
7%318%50%22%1
704
21st to endNight
7%5%18%47%21%2
592
March1st to 10thNight
45%22%46%22%2
720
11th to 20thNight
6%316%41%29%6%
720
21st to endNight
4418%44%27%2
792
April1st to 10thNight
36%16%48%26%2
720
11th to 20thNight
37%20%45%23%2
641
21st to endNight
3421%45%23%3
540
May1st to 10thNight
15%20%45%27%1
540
11th to 20thNight
2319%45%29%2
531
21st to endNight
3316%47%31%1
584
June1st to 10thNight
2212%51%31%1
540
11th to 20thNight
1112%51%34%1
540
21st to endNight
119%43%44%3
540
July1st to 10thNight
29%38%48%2
525
11th to 20thNight
316%31%56%5%
522
21st to endNight
32428%55%8%
591
August1st to 10thNight
21326%58%10%
537
11th to 20thNight
11429%59%6%
534
21st to endNight
216%22%59%10%
757
September1st to 10thNight
426%30%53%6%
720
11th to 20thNight
127%36%48%5%
720
21st to endNight
228%42%40%6%
720
October1st to 10thNight
3211%46%37%2
720
11th to 20thNight
210%46%40%2
720
21st to endNight
2311%41%37%6%
792
November1st to 10thNight
3110%46%37%3
740
11th to 20thNight
219%45%38%4
760
21st to endNight
5%214%46%31%3
760
December1st to 10thNight
6%211%48%31%2
760
11th to 20thNight
8%311%50%26%2
760
21st to endNight
8%215%48%24%3
836
Page generated at 2024-01-09 23:25:00. Version ac07

Copyright 2024 Attilla Danko


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