Pageant Avenue Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pageant Avenue Observatory clear sky chart from 2005-11-05 to 2018-01-20.

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
73%
16768
28%
48527
26%
16724
74%
16724
41%
27291

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
72%
777
28%
2504
30%
776
74%
776
40%
1328
January16th to endNight
68%
788
32%
2364
32%
788
71%
788
38%
1337
February1st to 15thNight
72%
698
31%
2106
33%
698
75%
698
42%
1142
February16th to endNight
61%
632
25%
1895
28%
632
62%
632
29%
1188
March1st to 15thNight
70%
720
26%
2160
29%
720
72%
720
38%
1208
March16th to endNight
72%
768
23%
2034
22%
768
73%
768
37%
1253
April1st to 15thNight
67%
719
23%
1799
17%
719
67%
719
39%
1119
April16th to endNight
70%
720
25%
1800
17%
720
71%
720
43%
1093
May1st to 15thNight
67%
593
22%
1674
17%
593
67%
593
33%
1059
May16th to endNight
65%
561
19%
1685
15%
561
65%
561
29%
1099
June1st to 15thNight
67%
540
16%
1620
14%
540
67%
540
30%
1070
June16th to endNight
82%
540
24%
1620
21%
540
82%
540
50%
840
July1st to 15thNight
81%
510
19%
1530
16%
510
81%
510
42%
858
July16th to endNight
77%
645
22%
1668
16%
606
77%
606
39%
998
August1st to 15thNight
78%
717
25%
1790
16%
713
78%
713
49%
1018
August16th to endNight
83%
764
32%
1910
23%
764
83%
764
56%
1036
September1st to 15thNight
81%
720
30%
1869
27%
720
81%
720
51%
1030
September16th to endNight
83%
716
38%
1980
37%
716
83%
716
58%
956
October1st to 15thNight
79%
720
31%
1980
30%
720
80%
720
48%
1069
October16th to endNight
75%
768
35%
2295
38%
768
75%
768
45%
1198
November1st to 15thNight
80%
760
30%
2470
35%
760
81%
760
45%
1225
November16th to endNight
77%
780
32%
2535
38%
780
78%
780
41%
1315
December1st to 15thNight
70%
780
31%
2535
34%
780
71%
780
36%
1389
December16th to endNight
67%
832
32%
2704
33%
832
70%
832
38%
1463

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
5%413212347%62%
48988
Night
7%6%24323347%55%
48734
TransparencyDay
23%48%16%23%23%
48691
Night
28%49%14%20%22%
48533
SeeingDay
7%319%40%23%5%
6360
Night
8%17%28%39%13%
16780

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 15thDay
9%314323345%58%
1762
16th to endDay
10%5%23312436%55%
1963
February1st to 15thDay
8%313313336%58%
1751
16th to endDay
12%5%24414447%46%
1579
March1st to 15thDay
6%4132134410%55%
1800
16th to endDay
5%42422335%9%56%
2187
April1st to 15thDay
7%5%13323447%55%
2149
16th to endDay
6%32211125%7%65%
2160
May1st to 15thDay
7%424312347%59%
2277
16th to endDay
5%5%23212237%62%
2429
June1st to 15thDay
5%7%23313226%61%
2340
16th to endDay
1223111235%73%
2340
July1st to 15thDay
35%14313337%62%
2340
16th to endDay
331321346%8%62%
2382
August1st to 15thDay
1312212235%72%
2160
16th to endDay
1212212246%70%
2292
September1st to 15thDay
2312212347%69%
2091
16th to endDay
2211212236%74%
1980
October1st to 15thDay
4313313346%62%
1980
16th to endDay
7%32212235%68%
1925
November1st to 15thDay
5%31322335%6%61%
1719
16th to endDay
7%413322336%62%
1755
December1st to 15thDay
7%313323449%55%
1755
16th to endDay
11%313324237%55%
1872
January1st to 15thNight
8%31442435%6%56%
2504
16th to endNight
10%424223237%55%
2364
February1st to 15thNight
8%414213246%59%
2101
16th to endNight
13%5%35%5%23345%47%
1895
March1st to 15thNight
8%5%23214338%53%
2160
16th to endNight
7%7%2322446%8%50%
2034
April1st to 15thNight
10%6%24322247%51%
1799
16th to endNight
8%7%13222246%56%
1800
May1st to 15thNight
8%10%35%3123410%46%
1673
16th to endNight
10%11%34322338%45%
1684
June1st to 15thNight
6%13%36%31235%9%42%
1620
16th to endNight
16%3431225%10%58%
1620
July1st to 15thNight
38%3332345%9%51%
1620
16th to endNight
36%343245%5%9%50%
1782
August1st to 15thNight
26%2431325%10%55%
1800
16th to endNight
2424212248%63%
1910
September1st to 15thNight
3413312347%62%
1869
16th to endNight
3412111138%69%
1980
October1st to 15thNight
441232325%7%61%
1980
16th to endNight
8%5%12312335%61%
2295
November1st to 15thNight
5%423223335%63%
2470
16th to endNight
5%324423347%58%
2535
December1st to 15thNight
9%5%2432335%7%54%
2535
16th to endNight
11%313412346%56%
2704

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
28%36%14%21%24%
1763
16th to endDay
30%47%15%14%28%
1963
February1st to 15thDay
25%48%14%21%25%
1751
16th to endDay
35%5%9%14%24%11%
1579
March1st to 15thDay
25%49%19%20%21%
1800
16th to endDay
25%6%11%23%19%13%
2187
April1st to 15thDay
28%49%23%24%9%
2149
16th to endDay
18%5%11%21%23%18%
2160
May1st to 15thDay
26%48%20%24%16%
2277
16th to endDay
24%410%22%29%9%
2432
June1st to 15thDay
27%48%15%25%18%
2340
16th to endDay
15%27%10%23%40%
2340
July1st to 15thDay
22%39%13%23%27%
2201
16th to endDay
19%6%14%20%26%12%
2234
August1st to 15thDay
16%27%16%31%25%
2146
16th to endDay
15%29%14%32%25%
2292
September1st to 15thDay
16%47%12%31%27%
2091
16th to endDay
14%36%12%33%29%
1980
October1st to 15thDay
23%36%15%24%25%
1980
16th to endDay
19%36%13%20%36%
1925
November1st to 15thDay
23%47%16%15%31%
1719
16th to endDay
23%37%15%18%32%
1755
December1st to 15thDay
26%5%10%14%16%27%
1755
16th to endDay
30%39%15%21%18%
1872
January1st to 15thNight
27%37%14%19%26%
2504
16th to endNight
30%38%12%13%30%
2364
February1st to 15thNight
26%39%14%19%26%
2112
16th to endNight
39%46%12%21%15%
1895
March1st to 15thNight
30%49%17%16%21%
2160
16th to endNight
31%6%11%17%19%13%
2034
April1st to 15thNight
32%49%22%20%10%
1799
16th to endNight
30%312%17%19%17%
1800
May1st to 15thNight
35%6%11%15%14%16%
1674
16th to endNight
39%6%12%15%15%10%
1685
June1st to 15thNight
39%6%13%9%18%11%
1620
16th to endNight
23%211%11%20%30%
1620
July1st to 15thNight
28%311%12%21%22%
1530
16th to endNight
30%5%13%19%22%8%
1668
August1st to 15thNight
26%212%17%25%15%
1790
16th to endNight
20%210%12%29%24%
1910
September1st to 15thNight
23%37%11%28%24%
1869
16th to endNight
17%17%11%33%27%
1980
October1st to 15thNight
23%37%17%23%23%
1980
16th to endNight
26%26%11%18%35%
2295
November1st to 15thNight
22%48%16%15%32%
2470
16th to endNight
26%38%13%16%30%
2535
December1st to 15thNight
30%47%14%17%25%
2535
16th to endNight
29%410%14%19%22%
2704

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
21%116%33%24%2
151
16th to endDay
15%5%24%38%12%3
306
February1st to 15thDay
9%427%39%16%1
266
16th to endDay
11%7%36%30%12%1
238
March1st to 15thDay
8%6%25%39%14%5%
270
16th to endDay
5%7%27%41%14%3
288
April1st to 15thDay
8%6%34%34%11%4
269
16th to endDay
411%32%37%8%5%
270
May1st to 15thDay
12%6%28%35%15%1
288
16th to endDay
10%5%25%38%18%1
330
June1st to 15thDay
7%22%44%20%3
315
16th to endDay
39%45%33%7%
315
July1st to 15thDay
7%6%40%37%7%
305
16th to endDay
6%235%46%9%
327
August1st to 15thDay
38%46%34%6%
315
16th to endDay
4446%37%6%
332
September1st to 15thDay
5%13%53%23%3
315
16th to endDay
6%118%50%20%4
315
October1st to 15thDay
3430%40%18%2
315
16th to endDay
9%120%37%21%9%
281
November1st to 15thDay
6%214%37%29%8%
135
16th to endDay
11%5%15%27%30%8%
135
December1st to 15thDay
2314%40%31%7%
135
16th to endDay
11%211%32%31%11%
144
January1st to 15thNight
9%27%36%32%11%
780
16th to endNight
12%29%35%32%8%
788
February1st to 15thNight
9%18%34%34%10%
704
16th to endNight
13%211%39%28%5%
632
March1st to 15thNight
10%19%37%33%6%
720
16th to endNight
10%19%32%37%8%
768
April1st to 15thNight
12%211%35%31%6%
719
16th to endNight
11%29%33%33%9%
720
May1st to 15thNight
9%111%32%36%7%
594
16th to endNight
14%212%25%39%5%
563
June1st to 15thNight
10%110%34%38%5%
540
16th to endNight
35%23%58%8%
540
July1st to 15thNight
7%312%59%17%
510
16th to endNight
6%212%53%25%
645
August1st to 15thNight
6%215%52%21%
717
16th to endNight
5%18%51%33%
764
September1st to 15thNight
5%215%55%20%
720
16th to endNight
5%426%46%16%
716
October1st to 15thNight
5%6%32%43%10%
720
16th to endNight
9%7%26%36%19%
768
November1st to 15thNight
5%15%35%38%14%
760
16th to endNight
6%15%33%36%17%
780
December1st to 15thNight
10%19%37%31%11%
780
16th to endNight
13%211%32%29%10%
832
Page generated at 2018-01-21 09:19:29. Version ac04

Copyright 2018 A. Danko


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