Presbyterian Point
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Presbyterian Point 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
41%
24105
14%
74669
8%
24055
47%
24055
13%
55852

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
24%
757
16%
2459
7%
757
34%
757
11%
1844
January11th to 20thNight
25%
732
14%
2378
7%
732
35%
732
9%
1848
January21st to endNight
23%
792
17%
2574
7%
792
36%
792
12%
1919
February1st to 10thNight
23%
720
14%
2340
4%
720
36%
720
12%
1744
February11th to 20thNight
12%
700
13%
2241
2%
699
25%
699
10%
1696
February21st to endNight
22%
592
18%
1691
6%
592
35%
592
12%
1296
March1st to 10thNight
27%
720
18%
1980
7%
720
38%
720
16%
1448
March11th to 20thNight
24%
720
13%
1980
6%
720
32%
720
12%
1546
March21st to endNight
23%
792
13%
2178
5%
792
31%
792
13%
1698
April1st to 10thNight
26%
720
15%
1836
3%
720
34%
720
15%
1410
April11th to 20thNight
34%
711
20%
1775
6%
711
42%
711
20%
1308
April21st to endNight
38%
720
16%
1800
7%
720
41%
720
17%
1381
May1st to 10thNight
36%
598
13%
1678
5%
598
40%
598
14%
1280
May11th to 20thNight
41%
531
12%
1592
6%
531
46%
531
12%
1272
May21st to endNight
57%
574
12%
1736
9%
574
58%
574
15%
1328
June1st to 10thNight
59%
360
13%
1440
17%
360
61%
360
13%
1033
June11th to 20thNight
59%
360
12%
1440
14%
360
61%
360
11%
1089
June21st to endNight
67%
438
12%
1518
12%
438
69%
438
13%
1142
July1st to 10thNight
68%
525
10%
1575
8%
525
68%
525
16%
1199
July11th to 20thNight
72%
522
10%
1566
8%
522
73%
522
16%
1191
July21st to endNight
64%
591
9%
1672
7%
558
65%
558
15%
1303
August1st to 10thNight
62%
537
12%
1600
10%
534
63%
534
14%
1258
August11th to 20thNight
62%
601
12%
1665
9%
601
63%
601
15%
1311
August21st to endNight
64%
792
9%
1980
6%
792
65%
792
15%
1618
September1st to 10thNight
64%
720
17%
1800
12%
720
65%
720
20%
1381
September11th to 20thNight
58%
720
19%
1862
14%
720
60%
720
18%
1438
September21st to endNight
43%
720
12%
2047
8%
720
47%
720
15%
1602
October1st to 10thNight
51%
720
15%
2160
13%
720
56%
720
16%
1617
October11th to 20thNight
45%
720
18%
2160
14%
720
52%
720
14%
1611
October21st to endNight
44%
792
19%
2376
12%
792
53%
792
15%
1738
November1st to 10thNight
42%
740
18%
2221
12%
740
51%
740
18%
1580
November11th to 20thNight
39%
760
17%
2343
11%
760
47%
760
14%
1749
November21st to endNight
40%
760
15%
2655
11%
760
48%
760
12%
1936
December1st to 10thNight
26%
760
13%
2660
5%
760
38%
760
10%
2003
December11th to 20thNight
32%
760
16%
3181
9%
758
41%
758
10%
2257
December21st to endNight
27%
828
11%
4510
6%
817
38%
817
7%
2778

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%25%5%345%6%8%44%
74589
Night
14%5%25%5%3445%7%45%
75132
TransparencyDay
25%38%8%15%12%3
74310
Night
25%38%7%14%14%3
74930
SeeingDay
17%11%26%25%16%5%
14082
Night
17%10%27%30%15%1
24121

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 10thDay
16%7%25%42435%6%46%
1706
11th to 20thDay
17%7%34433347%44%
1644
21st to endDay
16%6%345%24446%47%
1782
February1st to 10thDay
14%6%26%5%445%5%8%41%
1620
11th to 20thDay
21%6%13423445%46%
1604
21st to endDay
19%7%25%5%3445%6%40%
1560
March1st to 10thDay
14%6%2432445%5%51%
1980
11th to 20thDay
16%5%36%5%2446%8%42%
1980
21st to endDay
17%7%35%5%44446%40%
2178
April1st to 10thDay
10%42423435%8%55%
2124
11th to 20thDay
11%424435%46%7%50%
2134
21st to endDay
13%5%26%5%346%5%7%45%
2160
May1st to 10thDay
12%5%346%25%6%6%9%42%
2296
11th to 20thDay
15%5%25%6%45%5%6%9%38%
2301
21st to endDay
12%6%25%5%45%5%6%9%40%
2535
June1st to 10thDay
10%435%5%36%5%7%10%43%
2520
11th to 20thDay
9%4245%45%5%7%9%46%
2520
21st to endDay
7%425%5%46%7%8%12%40%
2432
July1st to 10thDay
8%436%6%5%6%7%7%11%37%
2340
11th to 20thDay
6%426%6%5%7%7%8%11%40%
2340
21st to endDay
7%435%7%47%7%9%9%36%
2547
August1st to 10thDay
10%6%35%6%5%5%6%7%11%36%
2327
11th to 20thDay
11%6%37%6%46%6%7%9%35%
2218
21st to endDay
9%5%35%6%46%6%6%11%39%
2376
September1st to 10thDay
10%5%245%445%6%9%46%
2160
11th to 20thDay
14%5%26%5%445%5%8%43%
2093
21st to endDay
20%5%36%41445%7%40%
1913
October1st to 10thDay
17%5%35%423345%50%
1800
11th to 20thDay
15%5%2332245%5%54%
1800
21st to endDay
12%425%5%23445%56%
1980
November1st to 10thDay
14%42442345%6%54%
1857
11th to 20thDay
15%5%34323447%51%
1833
21st to endDay
15%41332345%6%51%
1521
December1st to 10thDay
16%6%36%5%245%5%7%40%
1520
11th to 20thDay
17%424323345%55%
1910
21st to endDay
16%6%25%43446%9%42%
2978
January1st to 10thNight
15%6%25%43445%6%46%
2459
11th to 20thNight
16%6%35%5%2445%6%43%
2378
21st to endNight
16%5%34334445%50%
2574
February1st to 10thNight
18%7%3443445%7%44%
2340
11th to 20thNight
20%7%3442445%6%42%
2241
21st to endNight
15%7%35%424447%46%
1691
March1st to 10thNight
13%5%245%2445%6%51%
1980
11th to 20thNight
17%5%35%5%35%45%7%42%
1980
21st to endNight
16%6%26%5%34447%43%
2178
April1st to 10thNight
14%5%25%42445%7%47%
1836
11th to 20thNight
12%424435%5%5%7%50%
1775
21st to endNight
14%434435%5%5%7%46%
1800
May1st to 10thNight
13%6%24435%47%8%44%
1678
11th to 20thNight
16%6%35%5%3446%8%40%
1592
21st to endNight
13%5%26%5%3445%9%44%
1736
June1st to 10thNight
10%425%6%446%7%10%43%
1440
11th to 20thNight
10%436%6%35%5%7%11%41%
1440
21st to endNight
8%4345%46%6%6%11%41%
1518
July1st to 10thNight
8%435%5%45%5%8%12%40%
1620
11th to 20thNight
5%5%25%6%46%7%9%10%41%
1620
21st to endNight
7%5%26%6%46%7%7%11%40%
1771
August1st to 10thNight
10%5%36%7%46%7%6%10%36%
1611
11th to 20thNight
9%6%26%7%46%6%7%9%37%
1665
21st to endNight
9%6%26%6%46%6%7%11%37%
1980
September1st to 10thNight
12%5%35%42445%9%48%
1800
11th to 20thNight
14%6%35%5%35%46%7%44%
1862
21st to endNight
20%7%35%5%3446%6%37%
2047
October1st to 10thNight
15%5%25%6%3345%6%46%
2160
11th to 20thNight
14%6%24423446%52%
2160
21st to endNight
12%425%43445%6%52%
2376
November1st to 10thNight
14%6%24423346%51%
2221
11th to 20thNight
13%5%245%2445%6%51%
2343
21st to endNight
14%4245%2445%6%51%
2655
December1st to 10thNight
17%7%35%5%3445%5%41%
2660
11th to 20thNight
17%6%25%424446%47%
3285
21st to endNight
16%7%35%42445%6%44%
4660

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
25%40%6%17%11%1
1707
11th to 20thDay
25%42%5%13%14%2
1644
21st to endDay
27%37%5%15%14%2
1782
February1st to 10thDay
26%37%7%14%13%3
1620
11th to 20thDay
26%37%415%14%4
1613
21st to endDay
29%36%9%10%11%4
1560
March1st to 10thDay
22%36%5%18%15%4
1980
11th to 20thDay
27%37%7%15%9%5%
1980
21st to endDay
33%37%7%13%9%2
2178
April1st to 10thDay
18%36%6%17%15%7%
2124
11th to 20thDay
22%36%7%14%16%5%
2134
21st to endDay
26%38%6%14%11%4
2160
May1st to 10thDay
25%38%11%14%10%2
2296
11th to 20thDay
30%40%7%13%7%2
2305
21st to endDay
26%39%10%16%9%
2535
June1st to 10thDay
24%39%9%17%11%1
2520
11th to 20thDay
24%39%9%16%9%2
2520
21st to endDay
23%41%10%15%9%2
2432
July1st to 10thDay
25%41%9%13%9%2
2275
11th to 20thDay
23%42%14%13%7%2
2271
21st to endDay
25%42%13%14%6%
2405
August1st to 10thDay
26%40%11%17%6%
2314
11th to 20thDay
30%39%9%14%7%1
2218
21st to endDay
28%40%10%12%8%2
2376
September1st to 10thDay
22%39%9%10%15%4
2160
11th to 20thDay
25%37%6%15%14%2
2093
21st to endDay
28%37%6%11%15%4
1913
October1st to 10thDay
25%36%414%17%3
1800
11th to 20thDay
23%36%418%15%3
1800
21st to endDay
22%37%5%15%17%4
1980
November1st to 10thDay
15%41%5%15%19%4
1857
11th to 20thDay
21%40%7%15%13%4
1833
21st to endDay
21%39%5%14%17%4
1521
December1st to 10thDay
24%40%7%13%15%2
1520
11th to 20thDay
23%31%6%18%15%7%
1906
21st to endDay
29%26%9%21%15%1
2978
January1st to 10thNight
23%41%6%14%13%3
2459
11th to 20thNight
25%42%6%13%11%2
2378
21st to endNight
26%37%5%15%14%3
2574
February1st to 10thNight
27%36%5%14%14%4
2340
11th to 20thNight
28%37%5%12%14%4
2243
21st to endNight
28%36%5%13%13%5%
1691
March1st to 10thNight
22%36%6%17%16%4
1980
11th to 20thNight
29%36%7%13%12%3
1980
21st to endNight
28%37%6%14%12%2
2178
April1st to 10thNight
25%37%5%11%16%5%
1836
11th to 20thNight
20%36%6%13%18%5%
1775
21st to endNight
25%37%6%16%12%4
1800
May1st to 10thNight
25%38%9%15%11%2
1678
11th to 20thNight
30%39%7%12%9%2
1593
21st to endNight
25%39%9%16%10%1
1737
June1st to 10thNight
23%39%11%15%13%
1440
11th to 20thNight
28%40%10%11%10%2
1440
21st to endNight
24%41%9%13%11%2
1518
July1st to 10thNight
23%41%12%13%8%3
1575
11th to 20thNight
21%43%13%13%7%3
1566
21st to endNight
24%42%12%15%6%
1672
August1st to 10thNight
27%40%11%13%9%1
1600
11th to 20thNight
28%39%9%13%9%2
1665
21st to endNight
28%41%10%14%5%2
1980
September1st to 10thNight
23%38%6%15%13%4
1800
11th to 20thNight
25%38%6%14%16%2
1862
21st to endNight
29%37%7%9%14%4
2047
October1st to 10thNight
25%37%413%18%3
2160
11th to 20thNight
26%37%5%14%14%4
2160
21st to endNight
23%37%414%17%5%
2376
November1st to 10thNight
16%41%6%13%19%5%
2221
11th to 20thNight
23%39%6%10%16%5%
2343
21st to endNight
22%39%412%17%4
2655
December1st to 10thNight
25%41%5%12%15%2
2660
11th to 20thNight
28%32%6%13%15%5%
3288
21st to endNight
29%25%7%21%18%2
4660

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
27%24%33%12%4
270
11th to 20thDay
25%27%37%9%2
248
21st to endDay
23%23%38%14%2
264
February1st to 10thDay
23%23%39%11%3
240
11th to 20thDay
38%26%29%7%
271
21st to endDay
29%20%34%16%2
346
March1st to 10thDay
24%21%34%15%6%
420
11th to 20thDay
24%22%35%14%41
420
21st to endDay
21%20%37%16%5%1
462
April1st to 10thDay
20%19%32%21%7%1
420
11th to 20thDay
18%15%34%20%10%4
412
21st to endDay
21%12%32%25%10%1
420
May1st to 10thDay
16%16%37%22%8%1
423
11th to 20thDay
18%8%26%32%14%3
447
21st to endDay
19%6%19%28%22%5%
485
June1st to 10thDay
11%5%28%30%21%6%
450
11th to 20thDay
10%7%22%31%22%8%
450
21st to endDay
9%5%21%37%21%7%
450
July1st to 10thDay
10%215%32%30%11%
445
11th to 20thDay
6%113%34%36%9%
444
21st to endDay
9%216%37%26%10%
488
August1st to 10thDay
13%5%18%28%26%10%
446
11th to 20thDay
10%214%31%32%10%
439
21st to endDay
9%215%30%26%17%
495
September1st to 10thDay
12%414%28%25%16%
450
11th to 20thDay
15%414%34%22%12%
450
21st to endDay
26%6%23%26%14%5%
450
October1st to 10thDay
20%7%22%23%22%5%
450
11th to 20thDay
14%10%30%24%18%4
450
21st to endDay
14%13%30%27%14%3
495
November1st to 10thDay
17%9%32%24%13%4
455
11th to 20thDay
20%15%29%23%11%1
428
21st to endDay
22%17%24%27%9%2
181
December1st to 10thDay
23%18%39%12%6%1
180
11th to 20thDay
24%16%32%23%32
180
21st to endDay
22%22%31%16%6%2
258
January1st to 10thNight
19%20%34%23%4
760
11th to 20thNight
23%16%32%25%5%
732
21st to endNight
19%17%37%24%2
792
February1st to 10thNight
22%17%35%22%4
720
11th to 20thNight
26%20%39%14%1
703
21st to endNight
19%15%41%22%3
592
March1st to 10thNight
18%16%37%26%4
720
11th to 20thNight
20%16%35%21%7%
720
21st to endNight
19%13%41%22%5%
792
April1st to 10thNight
18%15%37%24%6%
720
11th to 20thNight
15%14%34%27%9%1
711
21st to endNight
15%9%35%34%7%
720
May1st to 10thNight
16%11%32%29%11%
598
11th to 20thNight
18%7%27%33%14%
531
21st to endNight
16%217%39%26%1
576
June1st to 10thNight
12%219%44%21%1
360
11th to 20thNight
11%221%40%24%3
360
21st to endNight
8%214%50%23%3
438
July1st to 10thNight
10%113%39%35%3
525
11th to 20thNight
5%112%38%39%5%
522
21st to endNight
8%216%40%32%3
591
August1st to 10thNight
10%214%41%28%4
537
11th to 20thNight
12%211%39%32%4
601
21st to endNight
10%212%34%35%6%
792
September1st to 10thNight
13%213%36%31%5%
720
11th to 20thNight
15%417%31%31%4
720
21st to endNight
23%421%32%19%1
720
October1st to 10thNight
16%6%20%29%25%4
720
11th to 20thNight
17%10%24%30%18%1
720
21st to endNight
15%10%27%30%16%2
792
November1st to 10thNight
17%8%29%29%15%2
740
11th to 20thNight
16%11%29%33%10%1
760
21st to endNight
16%13%27%31%12%1
760
December1st to 10thNight
23%13%33%22%8%
760
11th to 20thNight
19%11%34%30%6%
760
21st to endNight
22%15%28%30%5%
836
Page generated at 2024-01-10 19:35:20. Version ac07

Copyright 2024 Attilla Danko


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