Burnt Chimney
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Burnt Chimney clear sky chart from 2005-11-05 to 2017-09-21.

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
44%
15843
22%
47146
13%
15804
53%
15804
27%
29726

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 15thNight
26%
718
24%
2327
9%
716
44%
716
22%
1415
January16th to endNight
24%
768
23%
2496
9%
768
42%
768
22%
1534
February1st to 15thNight
23%
702
22%
2287
8%
701
41%
701
24%
1377
February16th to endNight
23%
631
26%
1874
10%
631
41%
631
26%
1164
March1st to 15thNight
31%
720
24%
1980
12%
720
43%
720
28%
1259
March16th to endNight
32%
768
20%
2112
11%
768
40%
768
26%
1395
April1st to 15thNight
33%
718
21%
1865
7%
718
41%
718
30%
1196
April16th to endNight
41%
664
21%
1744
9%
664
47%
664
31%
1158
May1st to 15thNight
42%
540
16%
1620
7%
540
49%
540
23%
1086
May16th to endNight
57%
561
16%
1684
12%
561
60%
561
29%
1086
June1st to 15thNight
66%
540
16%
1620
15%
540
68%
540
31%
1004
June16th to endNight
73%
540
17%
1620
14%
540
75%
540
34%
985
July1st to 15thNight
69%
510
12%
1530
11%
510
70%
510
27%
1021
July16th to endNight
74%
564
17%
1595
15%
531
77%
531
32%
992
August1st to 15thNight
67%
539
19%
1609
15%
536
68%
536
28%
1037
August16th to endNight
70%
687
19%
1833
15%
687
71%
687
30%
1214
September1st to 15thNight
62%
720
24%
1868
18%
720
64%
720
32%
1230
September16th to endNight
48%
681
18%
1881
15%
681
51%
681
23%
1322
October1st to 15thNight
50%
660
26%
1978
24%
660
57%
660
28%
1229
October16th to endNight
45%
704
32%
2112
20%
704
60%
704
35%
1197
November1st to 15thNight
45%
700
28%
2119
19%
700
57%
700
32%
1226
November16th to endNight
39%
720
25%
2382
17%
720
52%
720
27%
1364
December1st to 15thNight
29%
720
21%
2514
11%
720
43%
720
20%
1563
December16th to endNight
25%
768
22%
2496
9%
768
40%
768
19%
1672

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
13%5%245%35%5%5%7%41%
47692
Night
13%42442445%7%45%
47339
Cloud CoverDay
14%4245%35%45%7%41%
47702
Night
14%42442445%7%45%
47343
TransparencyDay
39%7%12%21%15%3
47403
Night
37%6%11%22%17%4
47146
SeeingDay
17%7%20%23%21%10%
5635
Night
16%7%25%29%18%2
15849

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 15thDay
14%42342445%7%43%
1611
16th to endDay
12%7%245%34445%44%
1728
February1st to 15thDay
12%6%25%5%35%447%42%
1575
16th to endDay
14%5%25%5%3445%7%42%
1595
March1st to 15thDay
13%5%1442435%5%46%
1969
16th to endDay
18%6%25%425%445%41%
2112
April1st to 15thDay
10%423424448%49%
2083
16th to endDay
16%4245%3445%6%42%
2226
May1st to 15thDay
18%5%245%35%46%8%33%
2331
16th to endDay
13%315%5%46%5%7%8%38%
2431
June1st to 15thDay
10%3145%37%5%7%9%40%
2340
16th to endDay
7%425%6%36%6%7%9%40%
2340
July1st to 15thDay
10%5%26%6%47%6%7%9%31%
2340
16th to endDay
7%426%6%47%7%9%11%31%
2465
August1st to 15thDay
14%4246%47%6%7%10%30%
2340
16th to endDay
11%5%26%7%45%5%6%9%35%
2357
September1st to 15thDay
12%5%26%425%45%6%44%
2090
16th to endDay
24%6%24433437%34%
1872
October1st to 15thDay
19%412213335%51%
1650
16th to endDay
13%5%14424335%51%
1760
November1st to 15thDay
11%423333345%54%
1736
16th to endDay
15%414413446%48%
1573
December1st to 15thDay
13%3143445%5%7%45%
1440
16th to endDay
20%5%25%434336%40%
1728
January1st to 15thNight
14%5%23324445%48%
2327
16th to endNight
14%5%25%42435%5%45%
2496
February1st to 15thNight
15%5%24323346%46%
2285
16th to endNight
11%6%25%3245%5%7%45%
1874
March1st to 15thNight
14%4243245%5%6%45%
1968
16th to endNight
17%424324447%44%
2112
April1st to 15thNight
13%42432445%7%47%
1865
16th to endNight
15%325%32445%7%44%
1744
May1st to 15thNight
16%5%15%5%25%35%8%39%
1620
16th to endNight
12%314435%5%5%10%42%
1682
June1st to 15thNight
9%223425%5%7%11%44%
1620
16th to endNight
6%2145%335%7%11%48%
1620
July1st to 15thNight
8%424436%6%9%8%42%
1620
16th to endNight
43245%35%6%8%12%42%
1703
August1st to 15thNight
12%415%5%2346%10%42%
1620
16th to endNight
8%325%5%36%6%6%10%41%
1833
September1st to 15thNight
12%425%4245%47%46%
1868
16th to endNight
20%5%245%23447%37%
1881
October1st to 15thNight
17%413424335%48%
1978
16th to endNight
12%313323345%56%
2112
November1st to 15thNight
13%424313335%54%
2119
16th to endNight
15%313323446%50%
2382
December1st to 15thNight
15%5%35%42345%5%43%
2514
16th to endNight
17%5%25%5%34446%38%
2496

Percentage Cloud Cover SE (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 15thDay
15%41443445%8%44%
1611
16th to endDay
13%7%245%34445%45%
1728
February1st to 15thDay
12%6%25%435%447%42%
1575
16th to endDay
14%6%245%3445%6%42%
1595
March1st to 15thDay
13%5%24325%36%6%46%
1980
16th to endDay
19%425%33345%6%41%
2111
April1st to 15thDay
11%42341345%7%50%
2083
16th to endDay
17%4245%24446%42%
2226
May1st to 15thDay
18%5%345%35%45%8%33%
2331
16th to endDay
13%315%6%36%5%7%9%38%
2431
June1st to 15thDay
10%314446%6%7%8%40%
2340
16th to endDay
8%326%5%36%6%7%8%40%
2340
July1st to 15thDay
12%5%26%6%37%6%7%10%31%
2340
16th to endDay
7%436%7%47%7%9%10%32%
2465
August1st to 15thDay
14%425%5%47%6%7%10%31%
2340
16th to endDay
12%5%26%7%35%5%6%8%35%
2357
September1st to 15thDay
12%5%25%5%24446%45%
2090
16th to endDay
25%425%423446%35%
1872
October1st to 15thDay
20%412212345%51%
1650
16th to endDay
12%5%24424335%51%
1760
November1st to 15thDay
12%323323445%54%
1736
16th to endDay
16%414313347%48%
1573
December1st to 15thDay
13%41433445%7%45%
1440
16th to endDay
21%5%24433336%40%
1728
January1st to 15thNight
15%424324345%48%
2327
16th to endNight
15%5%24325%346%45%
2496
February1st to 15thNight
15%5%2432335%5%47%
2278
16th to endNight
12%5%244245%47%45%
1874
March1st to 15thNight
14%42442447%6%45%
1980
16th to endNight
17%424424347%44%
2112
April1st to 15thNight
14%5%14324347%47%
1865
16th to endNight
16%42442345%8%44%
1744
May1st to 15thNight
17%5%145%35%448%39%
1619
16th to endNight
12%315%435%45%10%43%
1682
June1st to 15thNight
9%313435%6%6%11%44%
1620
16th to endNight
6%3144335%6%11%48%
1620
July1st to 15thNight
8%324436%6%9%8%42%
1620
16th to endNight
5%2146%45%6%8%12%41%
1703
August1st to 15thNight
13%315%5%3346%10%41%
1620
16th to endNight
9%425%5%36%5%7%10%41%
1833
September1st to 15thNight
12%5%25%4245%5%6%46%
1868
16th to endNight
21%5%25%423446%38%
1881
October1st to 15thNight
18%314424325%48%
1978
16th to endNight
12%313323235%56%
2112
November1st to 15thNight
13%42431233455%
2119
16th to endNight
15%41332335%6%50%
2382
December1st to 15thNight
16%5%345%2435%5%44%
2514
16th to endNight
17%6%25%5%24447%38%
2496

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 15thDay
38%5%13%21%17%2
1612
16th to endDay
39%48%26%16%3
1728
February1st to 15thDay
39%5%10%23%18%3
1577
16th to endDay
40%5%12%23%15%2
1595
March1st to 15thDay
36%5%11%23%17%4
1980
16th to endDay
44%6%8%21%14%4
2112
April1st to 15thDay
32%5%13%26%16%7%
2083
16th to endDay
41%6%10%19%15%6%
2226
May1st to 15thDay
46%8%13%17%10%3
2331
16th to endDay
39%9%15%23%10%1
2435
June1st to 15thDay
37%9%16%22%12%
2340
16th to endDay
37%10%15%17%15%3
2340
July1st to 15thDay
44%9%15%14%12%2
2201
16th to endDay
39%11%17%19%12%
2310
August1st to 15thDay
44%9%14%20%10%
2327
16th to endDay
42%10%15%18%11%1
2357
September1st to 15thDay
37%7%13%19%19%2
2090
16th to endDay
49%5%9%17%17%
1872
October1st to 15thDay
34%49%27%18%4
1650
16th to endDay
35%39%25%20%6%
1760
November1st to 15thDay
32%49%18%27%8%
1736
16th to endDay
36%49%24%21%3
1573
December1st to 15thDay
38%6%11%21%17%5%
1440
16th to endDay
45%410%20%15%2
1728
January1st to 15thNight
38%5%10%19%20%6%
2327
16th to endNight
38%5%9%23%18%3
2496
February1st to 15thNight
38%48%24%19%4
2287
16th to endNight
37%5%10%26%17%3
1874
March1st to 15thNight
36%6%9%27%15%3
1980
16th to endNight
41%411%21%17%2
2112
April1st to 15thNight
36%5%11%23%17%5%
1865
16th to endNight
38%6%11%19%17%6%
1744
May1st to 15thNight
42%7%13%20%13%1
1620
16th to endNight
35%9%16%25%10%2
1684
June1st to 15thNight
31%10%18%24%13%1
1620
16th to endNight
29%10%16%21%18%3
1620
July1st to 15thNight
34%13%14%20%12%4
1530
16th to endNight
31%10%18%25%12%1
1595
August1st to 15thNight
36%9%16%20%16%1
1609
16th to endNight
36%9%15%24%12%2
1833
September1st to 15thNight
37%7%11%20%18%4
1868
16th to endNight
47%6%8%16%18%1
1881
October1st to 15thNight
39%48%24%20%3
1978
16th to endNight
31%47%27%24%5%
2112
November1st to 15thNight
33%47%19%25%9%
2119
16th to endNight
34%48%23%23%5%
2382
December1st to 15thNight
42%5%8%22%17%4
2514
16th to endNight
45%6%10%19%15%2
2496

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 15thDay
17%21%40%15%32
90
16th to endDay
21%34%28%13%2
96
February1st to 15thDay
22%28%40%6%2
90
16th to endDay
18%18%36%21%5%
137
March1st to 15thDay
18%16%29%26%8%
270
16th to endDay
20%13%27%28%8%1
288
April1st to 15thDay
15%16%24%25%14%2
270
16th to endDay
22%422%22%20%7%
270
May1st to 15thDay
22%10%31%18%10%7%
288
16th to endDay
15%219%24%23%14%
331
June1st to 15thDay
11%317%25%25%16%
315
16th to endDay
10%218%27%29%10%
315
July1st to 15thDay
15%13%27%30%12%
305
16th to endDay
8%6%27%33%23%
326
August1st to 15thDay
15%12%20%30%19%
313
16th to endDay
11%17%19%31%27%
332
September1st to 15thDay
17%213%16%26%22%
315
16th to endDay
30%29%20%22%14%
275
October1st to 15thDay
23%316%25%23%6%
255
16th to endDay
14%5%24%31%20%3
272
November1st to 15thDay
16%9%23%22%25%2
244
16th to endDay
13%17%18%30%18%2
82
December1st to 15thDay
20%13%31%21%11%1
60
16th to endDay
37%11%33%15%2
96
January1st to 15thNight
19%16%34%24%5%
720
16th to endNight
18%13%40%26%1
768
February1st to 15thNight
20%12%40%25%1
704
16th to endNight
16%13%43%23%2
631
March1st to 15thNight
15%12%35%30%4
720
16th to endNight
19%8%33%29%8%
768
April1st to 15thNight
16%13%32%27%9%
718
16th to endNight
17%5%28%31%15%
664
May1st to 15thNight
18%428%32%14%
540
16th to endNight
12%217%27%34%4
563
June1st to 15thNight
8%114%33%36%4
540
16th to endNight
7%110%37%37%4
540
July1st to 15thNight
9%19%34%39%4
510
16th to endNight
5%18%33%43%7%
564
August1st to 15thNight
13%6%35%38%4
539
16th to endNight
10%7%31%42%7%
687
September1st to 15thNight
13%111%29%37%5%
720
16th to endNight
23%314%23%31%3
681
October1st to 15thNight
19%5%18%30%21%4
660
16th to endNight
14%7%28%32%15%1
704
November1st to 15thNight
15%7%27%32%14%2
700
16th to endNight
18%11%26%28%13%
720
December1st to 15thNight
21%10%33%26%7%
720
16th to endNight
21%11%35%28%3
768
Page generated at 2017-09-22 07:35:37. Version ac04

Copyright 2017 A. Danko


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