Pte. au Baril
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pte. au Baril clear sky chart from 2005-11-05 to 2017-09-16.

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
31%
15069
12%
46713
8%
15032
36%
15032
16%
34012

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
15%
898
5%
2675
2%
895
17%
895
8%
2257
January16th to endNight
21%
798
9%
2526
5%
798
25%
798
10%
2020
February1st to 15thNight
19%
702
9%
2287
3%
701
27%
701
10%
1780
February16th to endNight
24%
631
10%
2012
4%
631
30%
631
13%
1545
March1st to 15thNight
25%
720
13%
2007
6%
720
31%
720
17%
1469
March16th to endNight
35%
768
19%
2112
12%
768
42%
768
26%
1425
April1st to 15thNight
27%
680
14%
1797
6%
680
32%
680
20%
1332
April16th to endNight
35%
540
17%
1620
10%
540
40%
540
21%
1112
May1st to 15thNight
41%
479
15%
1559
13%
479
46%
479
22%
1034
May16th to endNight
45%
375
13%
1497
12%
374
54%
374
23%
871
June1st to 15thNight
49%
360
11%
1287
12%
360
53%
360
22%
808
June16th to endNight
51%
360
12%
1260
12%
360
56%
360
25%
778
July1st to 15thNight
60%
340
15%
1190
18%
340
64%
340
33%
659
July16th to endNight
52%
465
15%
1444
15%
436
53%
436
27%
873
August1st to 15thNight
54%
539
16%
1609
13%
536
58%
536
30%
990
August16th to endNight
53%
582
19%
1728
12%
582
58%
582
30%
1074
September1st to 15thNight
48%
720
15%
1839
8%
720
51%
720
33%
1203
September16th to endNight
45%
658
18%
1822
12%
658
49%
658
28%
1199
October1st to 15thNight
30%
660
14%
1980
10%
660
36%
660
16%
1456
October16th to endNight
19%
704
10%
2144
4%
704
27%
704
11%
1678
November1st to 15thNight
25%
700
13%
2408
11%
700
31%
700
12%
1777
November16th to endNight
18%
720
6%
2520
5%
720
21%
720
8%
2046
December1st to 15thNight
14%
720
3%
2520
1%
720
15%
720
5%
2183
December16th to endNight
13%
950
6%
2870
2%
950
17%
950
7%
2443

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
17%8%36%5%3445%7%34%
48034
Night
18%11%46%5%34446%30%
46880
Cloud CoverDay
17%9%36%5%3445%7%34%
48044
Night
18%11%46%5%34446%30%
46884
TransparencyDay
49%6%12%20%9%
47719
Night
54%5%12%17%8%
46713
SeeingDay
20%9%29%25%11%3
5793
Night
23%9%27%25%11%1
15073

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
20%17%6%9%6%23346%19%
1262
16th to endDay
15%17%7%8%6%44445%21%
1695
February1st to 15thDay
14%14%5%9%6%3445%6%23%
1575
16th to endDay
14%15%7%9%6%3333427%
1461
March1st to 15thDay
16%9%46%435%5%46%32%
1942
16th to endDay
13%7%26%43445%7%39%
2112
April1st to 15thDay
20%8%44434446%32%
2161
16th to endDay
18%7%24423336%41%
2340
May1st to 15thDay
19%6%35%424446%37%
2391
16th to endDay
14%4243345%5%9%42%
2618
June1st to 15thDay
15%5%26%5%35%5%6%8%35%
2671
16th to endDay
13%5%35%6%25%5%5%9%37%
2700
July1st to 15thDay
11%4245%2445%8%46%
2700
16th to endDay
10%42443446%9%44%
2617
August1st to 15thDay
11%5%144245%5%8%45%
2340
16th to endDay
12%6%25%5%3445%7%40%
2462
September1st to 15thDay
15%5%25%42446%6%40%
2120
16th to endDay
20%5%24423437%40%
1810
October1st to 15thDay
22%8%36%433346%33%
1650
16th to endDay
31%8%37%5%34335%22%
1727
November1st to 15thDay
24%9%46%5%345%5%7%24%
1449
16th to endDay
25%17%5%5%5%4434418%
1440
December1st to 15thDay
21%21%7%9%5%3444414%
1440
16th to endDay
20%21%6%8%5%33445%15%
1351
January1st to 15thNight
20%17%7%10%6%3444317%
2675
16th to endNight
16%17%7%9%6%34346%20%
2526
February1st to 15thNight
12%17%7%10%6%35%35%5%22%
2285
16th to endNight
16%13%5%9%7%44445%24%
2012
March1st to 15thNight
16%13%46%434346%31%
1995
16th to endNight
13%7%37%423345%42%
2112
April1st to 15thNight
21%10%36%424345%33%
1797
16th to endNight
18%7%26%5%23447%35%
1620
May1st to 15thNight
17%7%25%5%245%5%8%35%
1559
16th to endNight
12%6%243245%7%8%41%
1495
June1st to 15thNight
14%6%345%35%45%9%38%
1287
16th to endNight
12%5%24435%5%6%9%41%
1260
July1st to 15thNight
10%42333446%8%47%
1260
16th to endNight
10%4244245%6%8%45%
1546
August1st to 15thNight
11%4145%335%5%8%46%
1620
16th to endNight
12%5%145%2445%6%46%
1728
September1st to 15thNight
14%42343446%8%44%
1839
16th to endNight
15%6%15%424448%41%
1822
October1st to 15thNight
23%8%26%5%34335%32%
1980
16th to endNight
31%8%36%433345%25%
2144
November1st to 15thNight
22%11%46%43445%6%28%
2408
16th to endNight
27%16%46%5%3443419%
2520
December1st to 15thNight
23%20%6%8%6%3444414%
2520
16th to endNight
24%18%6%8%6%33345%15%
2870

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
20%17%7%10%5%23245%19%
1262
16th to endDay
16%16%7%9%6%34346%21%
1695
February1st to 15thDay
15%15%6%10%6%3435%6%23%
1575
16th to endDay
14%16%6%8%6%2433427%
1461
March1st to 15thDay
16%9%37%5%35%447%32%
1953
16th to endDay
13%7%36%4245%5%7%39%
2111
April1st to 15thDay
20%8%35%42445%6%32%
2161
16th to endDay
18%8%24424346%40%
2340
May1st to 15thDay
20%6%25%43445%6%36%
2391
16th to endDay
14%415%3245%6%9%42%
2618
June1st to 15thDay
15%5%25%5%245%7%8%35%
2671
16th to endDay
13%5%35%5%35%46%9%37%
2700
July1st to 15thDay
11%424435%35%8%46%
2700
16th to endDay
11%424425%5%6%9%44%
2617
August1st to 15thDay
11%5%245%345%5%8%44%
2340
16th to endDay
13%5%25%6%3445%8%39%
2462
September1st to 15thDay
15%5%25%42436%7%40%
2120
16th to endDay
19%6%15%424437%40%
1810
October1st to 15thDay
22%8%36%424246%32%
1650
16th to endDay
31%8%36%6%34335%22%
1727
November1st to 15thDay
24%10%46%43445%7%24%
1449
16th to endDay
25%17%5%5%5%35%335%18%
1440
December1st to 15thDay
22%22%6%9%424345%13%
1440
16th to endDay
21%21%6%8%5%24335%16%
1351
January1st to 15thNight
21%17%7%10%6%3443417%
2675
16th to endNight
16%17%7%10%6%34335%20%
2526
February1st to 15thNight
12%17%5%11%6%35%35%6%21%
2278
16th to endNight
16%12%6%9%7%45%445%24%
2012
March1st to 15thNight
17%13%47%433446%31%
2007
16th to endNight
13%7%47%422345%42%
2112
April1st to 15thNight
22%10%36%324346%32%
1797
16th to endNight
19%7%36%424338%35%
1620
May1st to 15thNight
17%7%25%5%246%5%7%36%
1558
16th to endNight
12%6%25%3245%7%9%41%
1495
June1st to 15thNight
14%7%2443446%7%39%
1287
16th to endNight
12%5%245%35%5%5%9%41%
1260
July1st to 15thNight
10%42342446%8%48%
1260
16th to endNight
10%42443447%8%45%
1546
August1st to 15thNight
12%4145%2445%8%45%
1620
16th to endNight
12%5%2442346%7%45%
1728
September1st to 15thNight
15%41442445%8%44%
1839
16th to endNight
15%6%25%424448%42%
1822
October1st to 15thNight
25%8%25%5%34335%32%
1980
16th to endNight
30%9%36%423346%24%
2144
November1st to 15thNight
22%12%36%5%23446%28%
2408
16th to endNight
27%16%47%5%23345%18%
2520
December1st to 15thNight
23%21%6%8%5%3334413%
2520
16th to endNight
24%19%7%8%5%3433416%
2870

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
68%6%12%11%2
1263
16th to endDay
66%6%8%12%5%
1695
February1st to 15thDay
61%6%9%17%4
1577
16th to endDay
59%5%10%16%7%
1461
March1st to 15thDay
51%6%14%18%8%
1953
16th to endDay
42%6%12%19%15%3
2112
April1st to 15thDay
51%6%8%19%12%1
2161
16th to endDay
44%410%23%14%2
2340
May1st to 15thDay
47%5%10%21%13%1
2391
16th to endDay
37%7%15%23%14%1
2622
June1st to 15thDay
43%7%11%24%12%
2671
16th to endDay
42%8%12%23%11%1
2700
July1st to 15thDay
32%7%15%29%13%1
2541
16th to endDay
35%8%14%27%13%
2456
August1st to 15thDay
35%8%16%25%12%
2327
16th to endDay
40%8%16%26%8%
2462
September1st to 15thDay
41%7%14%27%8%
2120
16th to endDay
43%7%14%25%8%
1810
October1st to 15thDay
53%5%12%17%10%
1650
16th to endDay
65%5%13%10%5%
1727
November1st to 15thDay
58%7%12%15%5%
1449
16th to endDay
70%5%13%7%2
1440
December1st to 15thDay
73%5%10%8%1
1440
16th to endDay
71%5%13%6%2
1351
January1st to 15thNight
71%5%10%9%3
2675
16th to endNight
66%410%11%5%
2526
February1st to 15thNight
63%5%13%13%4
2287
16th to endNight
61%412%14%6%
2012
March1st to 15thNight
53%413%19%8%
2007
16th to endNight
44%411%19%16%3
2112
April1st to 15thNight
53%47%19%13%1
1797
16th to endNight
49%39%18%17%2
1620
May1st to 15thNight
45%5%11%20%13%2
1559
16th to endNight
37%6%14%23%16%1
1497
June1st to 15thNight
42%6%13%22%14%1
1287
16th to endNight
38%6%15%25%13%
1260
July1st to 15thNight
31%5%14%28%17%2
1190
16th to endNight
36%7%14%27%13%
1444
August1st to 15thNight
35%6%16%26%13%
1609
16th to endNight
36%6%16%28%11%1
1728
September1st to 15thNight
37%5%18%26%10%1
1839
16th to endNight
41%5%15%29%8%
1822
October1st to 15thNight
56%411%17%10%
1980
16th to endNight
63%413%13%5%
2144
November1st to 15thNight
56%6%13%17%5%
2408
16th to endNight
68%414%9%1
2520
December1st to 15thNight
74%6%11%5%1
2520
16th to endNight
73%410%7%3
2870

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
26%19%36%14%3
61
16th to endDay
40%8%20%25%41
96
February1st to 15thDay
33%16%38%11%
90
16th to endDay
35%13%33%17%
81
March1st to 15thDay
22%17%29%23%5%1
243
16th to endDay
19%10%35%22%9%3
288
April1st to 15thDay
25%8%32%20%11%1
270
16th to endDay
22%13%30%19%10%4
270
May1st to 15thDay
25%6%27%22%12%5%
288
16th to endDay
16%11%30%25%12%3
331
June1st to 15thDay
17%9%32%27%11%1
466
16th to endDay
14%6%33%32%10%2
495
July1st to 15thDay
13%430%31%16%3
475
16th to endDay
11%430%32%16%4
380
August1st to 15thDay
14%422%32%15%10%
313
16th to endDay
20%6%18%26%17%8%
332
September1st to 15thDay
16%5%25%22%21%7%
315
16th to endDay
21%7%23%28%14%4
254
October1st to 15thDay
27%5%32%23%9%
255
16th to endDay
32%15%28%20%21
239
November1st to 15thDay
23%11%38%17%5%1
67
16th to endDay
33%16%28%21%
60
December1st to 15thDay
33%20%33%10%3
60
16th to endDay
34%34%26%31
64
January1st to 15thNight
29%15%30%20%41
900
16th to endNight
24%11%32%23%7%
798
February1st to 15thNight
23%15%32%22%6%
704
16th to endNight
22%11%33%26%6%
631
March1st to 15thNight
22%15%30%25%5%
720
16th to endNight
17%7%32%30%12%1
768
April1st to 15thNight
25%9%31%26%7%
680
16th to endNight
22%8%27%24%16%
540
May1st to 15thNight
20%5%23%33%15%2
479
16th to endNight
15%428%32%17%
375
June1st to 15thNight
18%421%36%17%1
360
16th to endNight
14%322%36%20%1
360
July1st to 15thNight
10%218%42%23%2
340
16th to endNight
12%324%32%24%2
465
August1st to 15thNight
14%219%35%22%6%
539
16th to endNight
15%421%30%25%3
582
September1st to 15thNight
17%5%24%27%18%7%
720
16th to endNight
17%6%25%28%17%4
658
October1st to 15thNight
28%8%26%23%11%1
660
16th to endNight
34%13%26%20%4
704
November1st to 15thNight
27%13%26%21%10%
700
16th to endNight
35%14%24%19%5%
720
December1st to 15thNight
34%17%27%15%4
720
16th to endNight
34%13%29%18%3
950
Page generated at 2017-09-16 17:07:00. Version ac04

Copyright 2017 A. Danko


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