Highlands Wilderness Observatory
Clear Sky Chart
History

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

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
28%
22665
13%
74565
8%
22619
35%
22619
15%
53627

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
11%
759
9%
2649
3%
757
18%
757
6%
2166
January11th to 20thNight
15%
724
9%
2488
4%
724
21%
724
7%
2006
January21st to endNight
21%
792
12%
2574
8%
792
27%
792
11%
2000
February1st to 10thNight
11%
720
8%
2340
2%
720
18%
720
8%
1889
February11th to 20thNight
16%
700
13%
2275
3%
700
28%
700
11%
1723
February21st to endNight
17%
592
13%
1884
3%
592
28%
592
11%
1426
March1st to 10thNight
17%
720
17%
2001
7%
720
26%
720
16%
1451
March11th to 20thNight
20%
720
16%
1980
7%
720
29%
720
16%
1448
March21st to endNight
25%
792
19%
2174
8%
792
34%
792
21%
1517
April1st to 10thNight
19%
720
14%
1800
5%
720
24%
720
18%
1384
April11th to 20thNight
25%
682
19%
1746
7%
682
32%
682
22%
1241
April21st to endNight
27%
540
16%
1620
8%
540
34%
540
17%
1161
May1st to 10thNight
35%
469
16%
1549
10%
469
43%
469
20%
1006
May11th to 20thNight
34%
354
22%
1416
16%
354
50%
354
21%
828
May21st to endNight
42%
389
16%
1551
13%
388
54%
388
26%
848
June1st to 10thNight
36%
360
11%
1440
9%
360
48%
360
18%
891
June11th to 20thNight
44%
360
14%
1440
17%
360
51%
360
22%
836
June21st to endNight
42%
360
12%
1266
12%
360
48%
360
21%
820
July1st to 10thNight
52%
350
16%
1350
20%
350
58%
350
29%
727
July11th to 20thNight
50%
348
17%
1392
22%
348
55%
348
25%
788
July21st to endNight
52%
452
17%
1541
15%
427
58%
427
29%
876
August1st to 10thNight
56%
537
17%
1600
13%
534
60%
534
34%
946
August11th to 20thNight
58%
534
18%
1598
11%
534
63%
534
31%
981
August21st to endNight
46%
688
18%
1876
8%
688
51%
688
30%
1230
September1st to 10thNight
44%
720
16%
1800
7%
720
47%
720
32%
1193
September11th to 20thNight
48%
720
24%
1846
14%
720
53%
720
36%
1169
September21st to endNight
43%
720
21%
2051
15%
720
49%
720
24%
1399
October1st to 10thNight
35%
720
15%
2160
11%
720
41%
720
19%
1517
October11th to 20thNight
23%
720
12%
2160
6%
720
31%
720
14%
1639
October21st to endNight
19%
792
14%
2376
6%
792
28%
792
12%
1843
November1st to 10thNight
28%
740
16%
2530
12%
740
36%
740
16%
1747
November11th to 20thNight
18%
760
13%
2660
6%
760
27%
760
12%
1947
November21st to endNight
19%
760
8%
2660
5%
760
24%
760
8%
2098
December1st to 10thNight
12%
760
7%
2660
3%
760
18%
760
6%
2205
December11th to 20thNight
13%
760
8%
3261
2%
759
20%
759
6%
2539
December21st to endNight
11%
831
5%
4851
1%
817
16%
817
3%
4142

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
17%11%47%6%35%5%5%6%31%
74868
Night
17%12%47%6%3445%6%31%
74800
TransparencyDay
53%5%10%20%10%1
74577
Night
54%5%10%19%10%1
74625
SeeingDay
24%14%31%20%9%3
13457
Night
24%12%29%24%10%1
22674

By Month

Percentage Cloud Cover NE (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
16%18%8%11%8%45%44419%
1517
11th to 20thDay
18%19%9%10%5%3443421%
1480
21st to endDay
13%15%9%13%7%44445%21%
1782
February1st to 10thDay
15%16%8%14%9%45%34419%
1620
11th to 20thDay
15%14%6%13%8%35%44426%
1573
21st to endDay
17%17%7%9%7%45%44422%
1371
March1st to 10thDay
15%14%5%8%8%46%445%27%
1954
11th to 20thDay
13%16%6%8%6%445%45%29%
1980
21st to endDay
20%12%35%5%34445%35%
2182
April1st to 10thDay
21%14%46%5%3435%6%28%
2160
11th to 20thDay
22%10%35%5%2434437%
2178
21st to endDay
22%11%46%5%34345%32%
2340
May1st to 10thDay
20%8%36%6%35%5%46%33%
2409
11th to 20thDay
16%8%36%5%35%447%38%
2478
21st to endDay
15%5%26%5%45%45%8%40%
2725
June1st to 10thDay
21%7%36%5%345%5%8%34%
2520
11th to 20thDay
15%6%36%5%35%5%6%9%36%
2520
21st to endDay
17%7%36%5%45%5%6%8%35%
2682
July1st to 10thDay
12%5%245%35%6%6%10%42%
2561
11th to 20thDay
12%7%25%5%46%5%6%8%39%
2520
21st to endDay
12%6%36%6%46%6%6%9%36%
2683
August1st to 10thDay
13%6%26%6%35%6%7%8%36%
2327
11th to 20thDay
13%6%26%6%36%5%7%8%37%
2303
21st to endDay
14%6%26%5%45%6%7%9%37%
2462
September1st to 10thDay
15%6%26%6%3445%8%38%
2160
11th to 20thDay
14%5%25%5%4445%8%44%
2111
21st to endDay
18%8%35%5%35%5%5%6%37%
1908
October1st to 10thDay
21%10%27%6%34447%32%
1800
11th to 20thDay
26%11%37%6%35%5%5%6%23%
1800
21st to endDay
28%13%47%6%34345%22%
1980
November1st to 10thDay
17%12%36%6%445%5%6%31%
1544
11th to 20thDay
19%13%5%9%6%45%5%6%6%23%
1520
21st to endDay
22%19%6%8%6%34445%18%
1520
December1st to 10thDay
19%24%9%9%5%335%4415%
1520
11th to 20thDay
19%17%6%10%7%3444423%
1906
21st to endDay
26%21%6%11%42333416%
2772
January1st to 10thNight
19%19%7%11%8%43345%17%
2649
11th to 20thNight
19%18%7%10%7%35%34420%
2488
21st to endNight
13%14%8%10%8%5%5%445%24%
2574
February1st to 10thNight
14%16%6%13%9%5%5%5%5%5%18%
2340
11th to 20thNight
14%14%7%11%6%45%445%26%
2273
21st to endNight
16%15%5%9%7%35%445%26%
1884
March1st to 10thNight
15%11%5%8%7%34446%33%
1991
11th to 20thNight
14%13%7%6%6%34445%33%
1979
21st to endNight
15%10%38%6%3445%6%37%
2174
April1st to 10thNight
21%13%47%5%35%346%29%
1800
11th to 20thNight
18%10%36%5%33447%37%
1746
21st to endNight
18%10%38%5%345%5%5%33%
1620
May1st to 10thNight
19%5%35%6%35%45%7%38%
1549
11th to 20thNight
15%5%345%345%6%6%44%
1415
21st to endNight
11%4245%345%6%8%47%
1550
June1st to 10thNight
16%7%25%5%36%47%8%36%
1440
11th to 20thNight
13%6%25%445%45%8%45%
1440
21st to endNight
15%7%36%446%46%7%39%
1266
July1st to 10thNight
9%5%25%435%46%8%50%
1390
11th to 20thNight
13%5%24435%5%6%8%45%
1440
21st to endNight
10%5%24435%5%5%8%47%
1632
August1st to 10thNight
10%5%25%42446%8%49%
1611
11th to 20thNight
9%5%346%46%5%6%9%45%
1598
21st to endNight
13%6%25%5%35%45%6%45%
1876
September1st to 10thNight
13%5%26%6%345%5%8%44%
1800
11th to 20thNight
14%5%245%2445%6%49%
1846
21st to endNight
18%7%25%6%43445%42%
2051
October1st to 10thNight
19%8%26%6%3445%7%35%
2160
11th to 20thNight
24%12%36%6%34446%27%
2160
21st to endNight
24%12%47%6%3445%5%25%
2376
November1st to 10thNight
21%10%36%5%34446%34%
2530
11th to 20thNight
18%14%5%6%6%35%45%7%27%
2660
21st to endNight
22%14%5%8%7%45%45%6%19%
2660
December1st to 10thNight
22%20%7%10%6%34445%15%
2660
11th to 20thNight
18%19%7%10%5%34345%21%
3288
21st to endNight
27%20%7%11%5%3333413%
4884

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
67%5%9%12%6%
1518
11th to 20thDay
68%48%9%10%1
1480
21st to endDay
66%46%10%11%2
1782
February1st to 10thDay
72%37%14%41
1620
11th to 20thDay
62%5%8%14%10%2
1582
21st to endDay
65%48%13%9%1
1371
March1st to 10thDay
58%5%12%14%9%1
1957
11th to 20thDay
58%47%18%11%2
1980
21st to endDay
52%47%18%15%4
2182
April1st to 10thDay
57%48%18%11%2
2160
11th to 20thDay
51%5%7%21%15%1
2178
21st to endDay
54%47%20%11%3
2340
May1st to 10thDay
51%48%21%13%3
2409
11th to 20thDay
47%5%7%24%15%1
2482
21st to endDay
43%6%12%21%15%3
2725
June1st to 10thDay
49%6%9%22%14%
2520
11th to 20thDay
43%6%11%24%14%2
2520
21st to endDay
46%6%13%22%11%1
2682
July1st to 10thDay
35%7%12%29%15%2
2491
11th to 20thDay
41%6%13%29%10%1
2445
21st to endDay
44%7%12%26%10%1
2533
August1st to 10thDay
43%8%12%25%11%1
2314
11th to 20thDay
42%8%14%25%10%1
2303
21st to endDay
42%7%13%27%11%1
2462
September1st to 10thDay
43%5%12%28%11%1
2160
11th to 20thDay
39%5%13%30%12%1
2111
21st to endDay
47%5%12%25%10%
1908
October1st to 10thDay
52%411%20%11%1
1800
11th to 20thDay
61%7%12%14%6%1
1800
21st to endDay
65%49%15%7%
1980
November1st to 10thDay
53%6%14%20%8%1
1544
11th to 20thDay
59%6%12%14%7%2
1520
21st to endDay
68%6%10%10%5%1
1520
December1st to 10thDay
74%48%10%41
1520
11th to 20thDay
67%6%8%11%8%1
1906
21st to endDay
74%46%12%4
2772
January1st to 10thNight
71%47%12%6%
2649
11th to 20thNight
69%47%11%7%1
2488
21st to endNight
62%5%7%14%10%1
2574
February1st to 10thNight
67%5%7%14%5%1
2340
11th to 20thNight
60%5%8%18%8%
2275
21st to endNight
60%49%18%8%
1884
March1st to 10thNight
53%5%11%17%13%2
2001
11th to 20thNight
54%49%20%11%2
1980
21st to endNight
49%48%22%14%3
2174
April1st to 10thNight
56%5%7%19%12%2
1800
11th to 20thNight
48%5%7%23%16%1
1746
21st to endNight
52%6%9%16%15%2
1620
May1st to 10thNight
47%410%19%17%3
1549
11th to 20thNight
40%5%8%26%18%3
1416
21st to endNight
34%5%15%25%17%3
1551
June1st to 10thNight
43%6%11%23%15%2
1440
11th to 20thNight
38%6%11%24%20%2
1440
21st to endNight
43%7%14%23%12%1
1266
July1st to 10thNight
32%6%12%28%21%2
1350
11th to 20thNight
35%7%12%30%16%
1392
21st to endNight
34%5%15%30%14%1
1541
August1st to 10thNight
33%6%19%28%14%1
1600
11th to 20thNight
34%7%18%25%15%1
1598
21st to endNight
39%6%13%29%12%1
1876
September1st to 10thNight
38%6%16%26%13%1
1800
11th to 20thNight
35%5%13%34%12%1
1846
21st to endNight
45%6%10%29%10%
2051
October1st to 10thNight
50%5%11%19%14%1
2160
11th to 20thNight
58%5%11%20%6%
2160
21st to endNight
62%5%9%14%9%1
2376
November1st to 10thNight
51%5%12%22%9%1
2530
11th to 20thNight
57%5%13%15%8%1
2660
21st to endNight
64%6%13%12%5%
2660
December1st to 10thNight
72%48%11%5%
2660
11th to 20thNight
66%411%13%6%
3288
21st to endNight
77%46%9%4
4884

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
24%21%34%13%6%2
180
11th to 20thDay
29%20%33%15%22
178
21st to endDay
25%15%39%14%5%1
264
February1st to 10thDay
31%28%32%8%3
240
11th to 20thDay
28%26%40%6%1
240
21st to endDay
39%21%29%11%
237
March1st to 10thDay
26%20%35%16%2
420
11th to 20thDay
29%17%34%16%31
420
21st to endDay
34%15%32%14%6%
462
April1st to 10thDay
29%20%29%16%6%1
420
11th to 20thDay
34%17%22%16%7%3
412
21st to endDay
30%15%33%12%8%1
420
May1st to 10thDay
29%13%28%20%5%5%
423
11th to 20thDay
22%14%33%18%10%3
447
21st to endDay
20%13%33%19%11%5%
485
June1st to 10thDay
23%10%34%25%7%1
450
11th to 20thDay
18%12%31%25%10%4
450
21st to endDay
20%10%33%26%9%2
612
July1st to 10thDay
11%8%33%27%15%5%
486
11th to 20thDay
18%6%27%27%15%6%
444
21st to endDay
12%10%34%29%10%5%
488
August1st to 10thDay
15%432%27%15%7%
446
11th to 20thDay
15%6%24%28%19%8%
439
21st to endDay
16%10%30%23%14%7%
495
September1st to 10thDay
14%11%30%23%15%6%
450
11th to 20thDay
15%8%26%23%20%9%
450
21st to endDay
21%13%25%24%11%5%
450
October1st to 10thDay
26%14%24%18%16%3
450
11th to 20thDay
29%17%33%16%41
450
21st to endDay
36%16%29%16%4
495
November1st to 10thDay
27%19%31%18%6%
236
11th to 20thDay
31%21%29%14%22
180
21st to endDay
33%15%43%7%21
180
December1st to 10thDay
33%17%29%18%2
180
11th to 20thDay
37%23%23%14%31
180
21st to endDay
37%19%31%10%3
198
January1st to 10thNight
33%18%29%16%5%
760
11th to 20thNight
29%15%31%18%6%1
724
21st to endNight
21%13%34%24%7%1
792
February1st to 10thNight
25%21%35%17%2
720
11th to 20thNight
23%19%35%18%4
703
21st to endNight
28%20%30%19%4
592
March1st to 10thNight
25%18%35%19%3
720
11th to 20thNight
24%17%34%19%5%1
720
21st to endNight
23%11%33%24%9%
792
April1st to 10thNight
28%15%32%20%5%
720
11th to 20thNight
26%13%32%20%9%1
682
21st to endNight
24%10%32%24%9%
540
May1st to 10thNight
24%6%28%28%13%2
469
11th to 20thNight
18%7%35%29%12%
354
21st to endNight
14%433%34%13%1
389
June1st to 10thNight
19%5%31%34%9%1
360
11th to 20thNight
15%9%25%37%13%
360
21st to endNight
18%7%24%36%14%1
360
July1st to 10thNight
10%6%25%41%18%1
350
11th to 20thNight
14%428%32%22%1
348
21st to endNight
11%326%40%19%
452
August1st to 10thNight
13%418%36%26%3
537
11th to 20thNight
10%6%17%37%27%3
534
21st to endNight
15%5%27%30%20%2
688
September1st to 10thNight
14%8%29%28%18%4
720
11th to 20thNight
16%424%31%21%4
720
21st to endNight
22%8%21%30%16%3
720
October1st to 10thNight
24%10%25%24%15%1
720
11th to 20thNight
31%13%27%21%8%1
720
21st to endNight
31%13%30%21%4
792
November1st to 10thNight
27%11%28%24%9%1
740
11th to 20thNight
28%15%33%17%6%1
760
21st to endNight
31%13%30%21%41
760
December1st to 10thNight
34%18%29%14%5%
760
11th to 20thNight
28%18%33%17%31
760
21st to endNight
35%14%31%17%3
836
Page generated at 2024-01-08 11:14:16. Version ac07

Copyright 2024 Attilla Danko


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