Presbyterian Point
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Presbyterian Point clear sky chart from 2005-11-05 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
42%
15684
22%
47051
13%
15648
51%
15648
26%
29758

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%
716
23%
2327
11%
716
42%
716
19%
1446
January16th to endNight
21%
768
24%
2496
10%
768
39%
768
21%
1537
February1st to 15thNight
21%
701
22%
2287
7%
701
40%
701
23%
1372
February16th to endNight
20%
631
27%
1874
10%
631
39%
631
25%
1127
March1st to 15thNight
28%
720
24%
1980
11%
720
41%
720
26%
1267
March16th to endNight
28%
768
21%
2112
10%
768
37%
768
25%
1389
April1st to 15thNight
31%
718
22%
1820
7%
718
42%
718
32%
1168
April16th to endNight
40%
720
21%
1800
8%
720
45%
720
31%
1185
May1st to 15thNight
37%
578
17%
1658
8%
578
43%
578
24%
1104
May16th to endNight
57%
555
17%
1677
12%
555
61%
555
29%
1065
June1st to 15thNight
62%
360
17%
1440
21%
360
65%
360
23%
860
June16th to endNight
68%
413
17%
1493
18%
413
70%
413
25%
913
July1st to 15thNight
67%
510
13%
1530
11%
510
68%
510
28%
988
July16th to endNight
67%
564
16%
1595
12%
531
69%
531
29%
1020
August1st to 15thNight
64%
539
17%
1609
15%
536
64%
536
25%
1083
August16th to endNight
66%
750
16%
1896
11%
750
67%
750
28%
1327
September1st to 15thNight
62%
720
24%
1800
17%
720
64%
720
33%
1206
September16th to endNight
47%
681
17%
1904
13%
681
50%
681
23%
1351
October1st to 15thNight
46%
660
26%
1980
23%
660
55%
660
27%
1257
October16th to endNight
43%
704
33%
2112
20%
704
61%
704
33%
1200
November1st to 15thNight
43%
700
26%
2101
17%
700
55%
700
31%
1240
November16th to endNight
41%
720
24%
2436
18%
720
53%
720
25%
1420
December1st to 15thNight
31%
720
20%
2520
12%
720
44%
720
20%
1578
December16th to endNight
27%
768
22%
2604
11%
768
41%
768
19%
1655

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
12%5%2443445%8%42%
47784
Night
13%5%2442445%7%44%
47245
Cloud CoverDay
12%5%2443445%7%43%
47794
Night
13%5%2442445%7%44%
47249
TransparencyDay
38%7%11%21%16%3
47495
Night
38%6%10%20%19%4
47052
SeeingDay
17%8%24%24%19%6%
5742
Night
16%8%26%30%16%1
15693

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
16%6%33424446%43%
1611
16th to endDay
17%6%23323346%46%
1728
February1st to 15thDay
14%6%24423446%44%
1575
16th to endDay
15%423424437%46%
1595
March1st to 15thDay
14%5%24424446%46%
1969
16th to endDay
17%5%2433445%6%41%
2112
April1st to 15thDay
10%32332335%7%52%
2128
16th to endDay
13%5%245%35%45%6%44%
2160
May1st to 15thDay
15%6%25%5%25%45%9%37%
2302
16th to endDay
9%5%25%5%45%5%6%9%40%
2434
June1st to 15thDay
8%3245%35%5%7%9%42%
2520
16th to endDay
6%335%5%45%5%6%11%41%
2462
July1st to 15thDay
7%426%6%47%7%8%10%34%
2340
16th to endDay
5%427%7%47%7%8%10%34%
2465
August1st to 15thDay
9%5%36%7%45%6%6%10%34%
2340
16th to endDay
10%5%16%6%46%7%7%11%33%
2294
September1st to 15thDay
9%4245%35%5%6%7%43%
2160
16th to endDay
21%6%25%433446%36%
1846
October1st to 15thDay
18%5%23312335%49%
1650
16th to endDay
11%423422335%55%
1760
November1st to 15thDay
15%5%13312436%51%
1757
16th to endDay
13%415%32335%5%50%
1519
December1st to 15thDay
14%5%24414447%45%
1440
16th to endDay
19%7%25%313346%41%
1617
January1st to 15thNight
15%5%2433345%6%44%
2327
16th to endNight
16%5%25%423345%45%
2496
February1st to 15thNight
16%6%23313347%47%
2285
16th to endNight
12%5%24413446%49%
1874
March1st to 15thNight
14%41443345%6%46%
1968
16th to endNight
16%5%25%4235%36%43%
2112
April1st to 15thNight
12%42342445%8%47%
1820
16th to endNight
14%414425%46%5%45%
1800
May1st to 15thNight
15%6%25%424449%39%
1658
16th to endNight
11%325%435%36%9%45%
1676
June1st to 15thNight
9%325%5%35%46%8%44%
1440
16th to endNight
7%3245%35%7%6%10%43%
1493
July1st to 15thNight
8%4145%36%5%8%10%40%
1620
16th to endNight
5%426%5%46%7%7%11%38%
1703
August1st to 15thNight
9%435%6%36%5%6%9%38%
1620
16th to endNight
8%436%5%35%6%7%10%36%
1896
September1st to 15thNight
12%5%25%42336%8%44%
1800
16th to endNight
18%6%26%5%3445%5%36%
1904
October1st to 15thNight
16%5%24423335%47%
1980
16th to endNight
12%413223345%55%
2112
November1st to 15thNight
12%424422345%52%
2101
16th to endNight
14%423324446%49%
2436
December1st to 15thNight
15%6%25%425%345%44%
2520
16th to endNight
19%7%24423336%41%
2604

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
16%6%24324345%44%
1611
16th to endDay
16%6%23423436%46%
1728
February1st to 15thDay
14%6%2443345%6%44%
1575
16th to endDay
15%424423346%46%
1595
March1st to 15thDay
14%5%2432435%6%47%
1980
16th to endDay
17%6%34334346%42%
2111
April1st to 15thDay
10%42332335%7%53%
2128
16th to endDay
12%5%25%4345%47%44%
2160
May1st to 15thDay
15%5%25%6%245%5%8%37%
2302
16th to endDay
9%5%245%35%5%6%9%40%
2434
June1st to 15thDay
9%4245%36%5%6%9%43%
2520
16th to endDay
6%3246%36%5%6%11%41%
2462
July1st to 15thDay
8%426%6%47%7%7%10%34%
2340
16th to endDay
5%435%7%5%7%7%9%9%34%
2465
August1st to 15thDay
10%6%36%6%45%5%7%10%34%
2340
16th to endDay
9%5%25%6%46%6%7%11%33%
2294
September1st to 15thDay
10%4145%445%6%8%44%
2160
16th to endDay
22%426%42345%6%36%
1846
October1st to 15thDay
19%5%2331224450%
1650
16th to endDay
11%42442233456%
1760
November1st to 15thDay
16%413313345%51%
1757
16th to endDay
14%424323346%49%
1519
December1st to 15thDay
15%425%414346%46%
1440
16th to endDay
19%6%35%313346%41%
1617
January1st to 15thNight
15%6%2443335%6%44%
2327
16th to endNight
17%43432344446%
2496
February1st to 15thNight
16%6%24313346%47%
2278
16th to endNight
12%6%33414446%48%
1874
March1st to 15thNight
14%42342435%7%47%
1980
16th to endNight
17%5%25%5%23445%44%
2112
April1st to 15thNight
12%41432445%8%47%
1820
16th to endNight
14%3244345%5%5%45%
1800
May1st to 15thNight
15%7%2432445%9%39%
1657
16th to endNight
11%325%43345%9%45%
1676
June1st to 15thNight
9%325%6%345%5%9%44%
1440
16th to endNight
6%3245%35%6%6%10%43%
1493
July1st to 15thNight
7%325%5%45%5%8%10%40%
1620
16th to endNight
5%5%146%46%6%7%11%39%
1703
August1st to 15thNight
9%5%26%6%35%6%5%9%39%
1620
16th to endNight
8%5%25%6%45%6%7%10%35%
1896
September1st to 15thNight
13%425%5%2435%9%45%
1800
16th to endNight
19%7%25%5%3445%5%36%
1904
October1st to 15thNight
16%5%25%5%2334447%
1980
16th to endNight
12%313323345%55%
2112
November1st to 15thNight
12%5%24413245%52%
2101
16th to endNight
15%423324445%49%
2436
December1st to 15thNight
16%6%25%5%24345%44%
2520
16th to endNight
19%6%34423336%42%
2604

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
41%5%7%20%20%3
1612
16th to endDay
38%48%23%18%6%
1728
February1st to 15thDay
38%48%23%20%4
1577
16th to endDay
37%413%21%18%4
1595
March1st to 15thDay
38%5%9%21%19%5%
1980
16th to endDay
42%5%10%21%15%4
2112
April1st to 15thDay
30%5%10%26%18%8%
2128
16th to endDay
39%6%10%18%18%7%
2160
May1st to 15thDay
43%7%14%20%12%2
2302
16th to endDay
37%9%14%25%11%1
2438
June1st to 15thDay
35%9%15%23%15%1
2520
16th to endDay
34%10%15%19%16%2
2462
July1st to 15thDay
39%11%16%16%12%3
2201
16th to endDay
38%11%17%19%11%1
2310
August1st to 15thDay
43%9%14%20%11%1
2327
16th to endDay
41%11%14%20%11%1
2294
September1st to 15thDay
37%9%12%15%21%3
2160
16th to endDay
47%6%9%17%18%2
1846
October1st to 15thDay
38%48%24%19%4
1650
16th to endDay
31%46%26%24%7%
1760
November1st to 15thDay
34%39%20%24%7%
1757
16th to endDay
34%49%21%24%4
1519
December1st to 15thDay
39%49%23%17%5%
1440
16th to endDay
44%311%20%17%3
1617
January1st to 15thNight
39%6%8%18%21%6%
2327
16th to endNight
40%47%22%19%4
2496
February1st to 15thNight
38%37%20%23%5%
2287
16th to endNight
35%49%23%21%4
1874
March1st to 15thNight
37%5%9%22%20%4
1980
16th to endNight
41%5%9%21%18%3
2112
April1st to 15thNight
35%5%9%22%21%6%
1820
16th to endNight
37%6%10%20%18%7%
1800
May1st to 15thNight
41%7%12%20%15%2
1658
16th to endNight
35%8%14%25%13%2
1678
June1st to 15thNight
36%9%15%21%15%1
1440
16th to endNight
34%10%14%19%17%3
1493
July1st to 15thNight
35%10%16%21%11%4
1530
16th to endNight
34%10%17%22%12%1
1595
August1st to 15thNight
39%10%16%17%14%1
1609
16th to endNight
39%10%16%20%11%2
1896
September1st to 15thNight
36%8%12%18%18%4
1800
16th to endNight
47%7%9%13%19%3
1904
October1st to 15thNight
40%47%19%22%4
1980
16th to endNight
31%36%24%25%8%
2112
November1st to 15thNight
34%48%16%26%9%
2101
16th to endNight
36%46%18%25%8%
2436
December1st to 15thNight
42%5%8%20%19%4
2520
16th to endNight
44%310%20%16%4
2604

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
23%18%47%10%
90
16th to endDay
23%32%32%11%
96
February1st to 15thDay
17%32%41%7%1
90
16th to endDay
19%21%37%20%2
200
March1st to 15thDay
22%17%33%18%7%
270
16th to endDay
16%16%36%20%8%1
288
April1st to 15thDay
16%15%30%24%11%2
270
16th to endDay
20%6%27%28%12%5%
270
May1st to 15thDay
22%14%30%19%10%2
288
16th to endDay
18%419%25%26%5%
331
June1st to 15thDay
10%423%24%25%11%
315
16th to endDay
8%323%32%25%6%
315
July1st to 15thDay
10%116%34%30%6%
305
16th to endDay
7%111%30%35%13%
326
August1st to 15thDay
16%116%25%26%14%
313
16th to endDay
9%11%30%31%16%
332
September1st to 15thDay
14%315%24%23%17%
315
16th to endDay
31%215%19%20%11%
275
October1st to 15thDay
25%6%22%20%19%5%
255
16th to endDay
12%10%26%27%20%2
272
November1st to 15thDay
19%8%29%23%15%3
265
16th to endDay
18%12%20%33%12%2
124
December1st to 15thDay
20%20%33%15%8%3
60
16th to endDay
35%20%27%10%6%
77
January1st to 15thNight
20%17%31%24%5%
720
16th to endNight
20%17%36%23%2
768
February1st to 15thNight
22%16%36%22%1
704
16th to endNight
15%18%42%21%2
631
March1st to 15thNight
18%13%37%25%5%
720
16th to endNight
18%11%36%24%8%
768
April1st to 15thNight
15%14%36%26%7%
718
16th to endNight
16%8%31%33%10%
720
May1st to 15thNight
19%7%30%30%11%
578
16th to endNight
14%117%38%26%
557
June1st to 15thNight
11%216%43%23%1
360
16th to endNight
7%115%47%26%1
413
July1st to 15thNight
9%13%39%33%3
510
16th to endNight
6%113%35%38%4
564
August1st to 15thNight
11%110%41%31%3
539
16th to endNight
10%19%38%33%6%
750
September1st to 15thNight
14%115%33%31%3
720
16th to endNight
22%218%30%24%1
681
October1st to 15thNight
19%5%21%29%20%3
660
16th to endNight
14%9%29%26%17%1
704
November1st to 15thNight
16%8%28%30%14%2
700
16th to endNight
17%13%24%29%14%1
720
December1st to 15thNight
20%11%31%25%10%
720
16th to endNight
24%13%30%28%4
768
Page generated at 2017-09-22 07:35:37. Version ac04

Copyright 2017 A. Danko


Presbyterian Point Clear Sky Chart | Charts Home