Geddy's Blue Room Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Geddy's Blue Room Observatory clear sky chart from 2005-11-05 to 2017-09-24.

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
61%
15849
21%
47029
17%
15808
65%
15808
31%
29108

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
44%
718
21%
2327
15%
716
53%
716
24%
1472
January16th to endNight
45%
768
24%
2406
19%
768
53%
768
27%
1498
February1st to 15thNight
46%
701
25%
2104
18%
698
54%
698
33%
1257
February16th to endNight
45%
631
23%
1876
14%
631
54%
631
30%
1162
March1st to 15thNight
50%
720
29%
1980
17%
720
60%
720
40%
1156
March16th to endNight
55%
768
28%
2112
20%
768
61%
768
40%
1211
April1st to 15thNight
60%
718
24%
1976
18%
718
65%
718
43%
1117
April16th to endNight
63%
672
28%
1833
20%
672
68%
672
43%
1029
May1st to 15thNight
73%
539
24%
1619
20%
539
76%
539
42%
883
May16th to endNight
75%
561
26%
1682
21%
561
77%
561
40%
944
June1st to 15thNight
69%
540
14%
1620
12%
540
69%
540
26%
1080
June16th to endNight
75%
540
10%
1620
9%
540
75%
540
24%
1112
July1st to 15thNight
73%
510
8%
1530
8%
510
73%
510
22%
1069
July16th to endNight
73%
564
6%
1595
6%
531
74%
531
22%
1136
August1st to 15thNight
73%
539
5%
1663
6%
536
73%
536
23%
1144
August16th to endNight
70%
675
11%
2012
11%
675
70%
675
22%
1406
September1st to 15thNight
68%
720
8%
1980
8%
720
68%
720
20%
1420
September16th to endNight
64%
693
16%
1914
15%
693
65%
693
22%
1348
October1st to 15thNight
71%
660
27%
1842
27%
660
72%
660
36%
1103
October16th to endNight
62%
704
29%
2112
27%
704
68%
704
35%
1231
November1st to 15thNight
62%
700
31%
2101
27%
700
69%
700
40%
1137
November16th to endNight
53%
720
28%
2289
23%
720
63%
720
34%
1311
December1st to 15thNight
52%
720
27%
2340
25%
720
59%
720
30%
1380
December16th to endNight
53%
768
23%
2496
22%
768
59%
768
28%
1502

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
8%425%5%35%6%7%9%40%
47881
Night
8%425%435%5%6%9%44%
47237
TransparencyDay
39%8%14%17%14%6%
47582
Night
35%7%15%20%15%6%
47040
SeeingDay
9%213%21%27%25%
5713
Night
10%217%31%28%9%
15857

By Month

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
12%5%25%43446%8%43%
1611
16th to endDay
10%4344245%5%6%47%
1815
February1st to 15thDay
13%5%35%5%2435%5%46%
1750
16th to endDay
8%5%25%41345%6%50%
1595
March1st to 15thDay
7%413425%45%7%53%
1980
16th to endDay
7%5%25%4335%48%50%
2111
April1st to 15thDay
7%3145%3446%8%51%
1972
16th to endDay
6%213425%36%8%53%
2136
May1st to 15thDay
6%21442446%9%54%
2331
16th to endDay
6%314446%7%7%11%43%
2431
June1st to 15thDay
10%5%35%5%46%7%9%11%31%
2340
16th to endDay
9%435%7%38%7%8%12%30%
2340
July1st to 15thDay
8%426%7%5%8%10%10%12%23%
2340
16th to endDay
7%438%9%5%9%9%11%11%20%
2465
August1st to 15thDay
10%426%6%48%10%11%13%19%
2283
16th to endDay
9%6%35%7%47%8%9%11%25%
2178
September1st to 15thDay
8%6%46%7%6%8%7%8%10%26%
1980
16th to endDay
9%6%28%8%45%6%8%9%28%
1905
October1st to 15thDay
7%5%26%6%35%46%7%44%
1785
16th to endDay
7%425%32445%7%50%
1760
November1st to 15thDay
6%41332345%7%54%
1757
16th to endDay
9%324433448%50%
1668
December1st to 15thDay
10%5%245%3446%7%44%
1620
16th to endDay
8%5%24425%5%6%8%45%
1728
January1st to 15thNight
11%7%35%5%3445%9%39%
2327
16th to endNight
15%3244335%5%7%43%
2406
February1st to 15thNight
11%5%24423346%49%
2103
16th to endNight
9%6%36%424446%46%
1876
March1st to 15thNight
6%425%32446%7%53%
1980
16th to endNight
8%42431335%7%55%
2112
April1st to 15thNight
6%32332445%9%54%
1976
16th to endNight
6%31332345%8%56%
1833
May1st to 15thNight
5%31332445%10%54%
1619
16th to endNight
5%214425%46%9%53%
1682
June1st to 15thNight
10%425%5%46%6%6%9%38%
1620
16th to endNight
6%425%5%46%6%9%14%34%
1620
July1st to 15thNight
5%5%25%7%38%7%10%12%31%
1620
16th to endNight
3437%7%47%9%9%13%27%
1703
August1st to 15thNight
6%5%26%6%26%8%10%14%30%
1674
16th to endNight
9%5%25%6%36%6%7%11%34%
2012
September1st to 15thNight
6%5%36%7%5%7%7%8%11%29%
1980
16th to endNight
9%5%36%7%45%8%7%10%32%
1914
October1st to 15thNight
7%4234345%5%8%50%
1842
16th to endNight
8%5%243235%48%50%
2112
November1st to 15thNight
6%323434447%55%
2101
16th to endNight
6%5%25%42445%8%49%
2289
December1st to 15thNight
10%425%32445%8%46%
2340
16th to endNight
9%5%25%435%46%8%43%
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
39%5%9%19%19%7%
1612
16th to endDay
36%47%17%23%10%
1815
February1st to 15thDay
40%35%15%18%16%
1752
16th to endDay
34%49%16%22%11%
1595
March1st to 15thDay
31%410%23%22%8%
1980
16th to endDay
33%5%11%20%19%10%
2112
April1st to 15thDay
31%5%13%18%23%8%
1972
16th to endDay
29%5%11%21%23%8%
2136
May1st to 15thDay
27%5%13%25%18%8%
2331
16th to endDay
33%7%15%23%15%4
2435
June1st to 15thDay
44%9%18%21%5%
2340
16th to endDay
45%12%20%16%4
2340
July1st to 15thDay
50%14%21%10%1
2201
16th to endDay
50%15%21%10%2
2310
August1st to 15thDay
49%14%25%9%
2270
16th to endDay
49%14%19%15%1
2178
September1st to 15thDay
49%12%20%11%5%
1980
16th to endDay
50%8%13%16%7%2
1905
October1st to 15thDay
40%48%15%18%11%
1785
16th to endDay
33%5%8%16%23%13%
1760
November1st to 15thDay
29%39%23%22%11%
1757
16th to endDay
34%48%19%19%13%
1668
December1st to 15thDay
37%5%12%20%18%6%
1620
16th to endDay
35%5%11%22%16%8%
1728
January1st to 15thNight
42%49%20%17%6%
2327
16th to endNight
39%48%14%23%9%
2406
February1st to 15thNight
35%38%16%21%14%
2112
16th to endNight
37%5%11%14%23%8%
1876
March1st to 15thNight
29%411%25%21%7%
1980
16th to endNight
29%410%25%19%10%
2112
April1st to 15thNight
26%5%15%22%24%5%
1976
16th to endNight
26%412%25%23%6%
1833
May1st to 15thNight
24%6%16%26%18%7%
1620
16th to endNight
28%5%16%27%19%2
1684
June1st to 15thNight
40%8%22%22%5%
1620
16th to endNight
38%13%23%21%3
1620
July1st to 15thNight
38%15%31%12%2
1530
16th to endNight
40%14%31%11%2
1595
August1st to 15thNight
38%14%35%10%1
1663
16th to endNight
41%12%26%17%2
2012
September1st to 15thNight
43%12%25%14%3
1980
16th to endNight
44%9%16%18%7%2
1914
October1st to 15thNight
30%6%12%20%19%9%
1842
16th to endNight
33%38%15%27%10%
2112
November1st to 15thNight
27%49%24%23%9%
2101
16th to endNight
33%38%21%18%14%
2289
December1st to 15thNight
34%5%9%27%16%6%
2340
16th to endNight
36%5%11%22%14%9%
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
13%436%23%16%5%
90
16th to endDay
14%10%39%18%15%1
96
February1st to 15thDay
8%17%26%26%15%4
90
16th to endDay
5%10%35%30%17%1
96
March1st to 15thDay
9%5%31%33%17%2
270
16th to endDay
13%419%29%27%4
288
April1st to 15thDay
8%6%19%32%25%7%
270
16th to endDay
5%117%28%34%12%
270
May1st to 15thDay
6%314%29%27%18%
288
16th to endDay
6%18%17%31%33%
331
June1st to 15thDay
13%25%13%24%40%
315
16th to endDay
7%310%28%50%
315
July1st to 15thDay
5%26%26%58%
305
16th to endDay
8%6%11%26%46%
326
August1st to 15thDay
14%37%23%51%
313
16th to endDay
11%311%28%44%
332
September1st to 15thDay
14%314%32%33%
315
16th to endDay
12%415%38%28%
287
October1st to 15thDay
10%19%34%32%12%
255
16th to endDay
10%117%32%30%7%
272
November1st to 15thDay
7%15%36%28%10%
265
16th to endDay
7%226%36%21%5%
138
December1st to 15thDay
10%145%28%12%2
90
16th to endDay
8%221%42%23%1
96
January1st to 15thNight
15%426%34%17%
720
16th to endNight
16%7%25%36%13%
768
February1st to 15thNight
14%429%36%14%1
704
16th to endNight
12%6%28%40%11%
631
March1st to 15thNight
9%5%29%40%13%1
720
16th to endNight
9%325%41%18%1
768
April1st to 15thNight
8%323%44%19%1
718
16th to endNight
8%221%41%25%
672
May1st to 15thNight
7%210%45%30%4
540
16th to endNight
7%16%35%39%10%
563
June1st to 15thNight
13%16%19%44%15%
540
16th to endNight
8%313%45%29%
540
July1st to 15thNight
6%311%39%39%
510
16th to endNight
439%47%35%
564
August1st to 15thNight
7%26%48%34%
539
16th to endNight
12%315%41%26%
675
September1st to 15thNight
10%5%20%43%19%
720
16th to endNight
11%7%24%45%9%
693
October1st to 15thNight
8%10%37%37%5%
660
16th to endNight
10%218%33%32%2
704
November1st to 15thNight
7%221%40%23%4
700
16th to endNight
7%326%40%19%1
720
December1st to 15thNight
12%325%36%20%
720
16th to endNight
11%322%37%22%1
768
Page generated at 2017-09-25 09:02:21. Version ac04

Copyright 2017 A. Danko


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