Area 63
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Area 63 clear sky chart from 2005-11-05 to 2018-01-12.

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
66%
16620
20%
48380
17%
16579
69%
16579
31%
30164

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
58%
764
19%
2472
16%
761
64%
761
28%
1493
January16th to endNight
55%
768
26%
2430
20%
768
63%
768
35%
1377
February1st to 15thNight
54%
702
26%
2108
22%
700
60%
700
35%
1235
February16th to endNight
62%
631
31%
1767
21%
631
71%
631
44%
970
March1st to 15thNight
60%
720
28%
1980
20%
720
67%
720
44%
1074
March16th to endNight
64%
768
29%
2112
24%
768
68%
768
42%
1190
April1st to 15thNight
71%
718
25%
1976
22%
718
74%
718
49%
1042
April16th to endNight
65%
720
26%
1839
19%
720
68%
720
45%
1071
May1st to 15thNight
77%
704
25%
1784
18%
704
78%
704
49%
986
May16th to endNight
77%
561
18%
1683
15%
561
77%
561
32%
1054
June1st to 15thNight
65%
540
8%
1620
7%
540
65%
540
17%
1223
June16th to endNight
76%
540
8%
1620
7%
540
76%
540
21%
1177
July1st to 15thNight
76%
510
5%
1530
5%
510
76%
510
20%
1148
July16th to endNight
81%
564
7%
1595
6%
531
82%
531
26%
1101
August1st to 15thNight
77%
569
6%
1639
6%
566
77%
566
23%
1166
August16th to endNight
65%
764
5%
2092
5%
764
65%
764
18%
1541
September1st to 15thNight
67%
720
4%
1980
5%
720
67%
720
19%
1461
September16th to endNight
60%
717
6%
1980
6%
717
61%
717
15%
1520
October1st to 15thNight
70%
720
19%
2063
19%
720
72%
720
30%
1319
October16th to endNight
60%
768
21%
2304
21%
768
63%
768
27%
1481
November1st to 15thNight
68%
760
30%
2281
27%
760
74%
760
40%
1266
November16th to endNight
60%
780
29%
2340
25%
780
65%
780
32%
1408
December1st to 15thNight
63%
780
26%
2481
25%
780
69%
780
34%
1417
December16th to endNight
68%
832
27%
2704
27%
832
72%
832
38%
1444

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
7%6%37%8%5%7%6%6%8%32%
48946
Night
6%425%5%35%5%7%9%44%
48583
TransparencyDay
45%9%14%15%11%3
48647
Night
33%9%18%21%13%3
48386
SeeingDay
8%19%20%28%31%
6404
Night
7%112%33%31%12%
16626

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
7%426%7%36%6%6%10%38%
1710
16th to endDay
8%5%26%5%35%5%5%8%43%
1791
February1st to 15thDay
10%5%35%435%46%7%43%
1750
16th to endDay
5%4245%445%5%10%46%
1706
March1st to 15thDay
3325%6%46%6%6%9%45%
1980
16th to endDay
6%416%6%46%5%5%8%43%
2111
April1st to 15thDay
5%325%7%47%6%6%10%39%
1972
16th to endDay
7%425%7%47%5%6%8%40%
2121
May1st to 15thDay
5%315%7%46%5%7%7%44%
2174
16th to endDay
9%6%37%9%5%7%7%6%7%28%
2431
June1st to 15thDay
13%8%410%10%6%7%7%7%7%16%
2340
16th to endDay
8%6%311%9%6%9%7%8%8%19%
2340
July1st to 15thDay
8%7%49%9%6%9%7%7%9%19%
2340
16th to endDay
6%7%49%11%6%9%8%7%9%19%
2465
August1st to 15thDay
6%7%38%10%6%8%8%8%10%21%
2298
16th to endDay
9%7%39%11%6%8%7%7%8%19%
2106
September1st to 15thDay
8%7%410%10%7%8%8%7%8%18%
1980
16th to endDay
11%10%5%9%10%6%8%8%5%7%16%
1980
October1st to 15thDay
7%6%38%10%48%6%7%9%28%
1896
16th to endDay
9%7%36%6%5%7%6%6%7%33%
1920
November1st to 15thDay
6%4245%47%5%5%8%46%
1907
16th to endDay
7%5%36%6%45%6%5%7%42%
1950
December1st to 15thDay
8%6%36%5%35%5%6%8%42%
1806
16th to endDay
6%4245%345%6%11%44%
1872
January1st to 15thNight
8%5%25%5%245%7%9%42%
2472
16th to endNight
5%4245%35%5%6%8%48%
2430
February1st to 15thNight
9%5%2433445%7%49%
2103
16th to endNight
421342445%10%55%
1767
March1st to 15thNight
421342346%9%56%
1980
16th to endNight
431442436%9%54%
2112
April1st to 15thNight
211342446%9%58%
1976
16th to endNight
5%31342446%8%54%
1839
May1st to 15thNight
21134245%7%9%57%
1784
16th to endNight
6%325%435%7%9%10%41%
1682
June1st to 15thNight
10%7%37%7%46%8%8%10%24%
1620
16th to endNight
5%5%26%6%47%7%9%11%31%
1620
July1st to 15thNight
5%5%37%6%46%8%7%12%31%
1620
16th to endNight
3335%6%38%8%9%12%34%
1703
August1st to 15thNight
45%26%6%47%8%8%13%32%
1650
16th to endNight
7%5%37%6%37%7%9%11%29%
2092
September1st to 15thNight
6%5%36%7%5%7%6%10%12%29%
1980
16th to endNight
8%7%37%8%47%7%8%9%25%
1980
October1st to 15thNight
6%5%25%5%35%6%8%10%42%
2063
16th to endNight
11%5%26%5%35%45%8%41%
2304
November1st to 15thNight
5%424425%35%8%53%
2281
16th to endNight
7%5%25%5%3445%8%48%
2340
December1st to 15thNight
6%425%435%45%8%49%
2481
16th to endNight
4324425%46%9%51%
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
39%7%13%18%14%5%
1711
16th to endDay
37%6%9%21%20%5%
1791
February1st to 15thDay
38%47%20%18%9%
1752
16th to endDay
31%6%11%23%19%7%
1706
March1st to 15thDay
31%7%11%24%19%6%
1980
16th to endDay
37%5%10%21%17%8%
2112
April1st to 15thDay
36%7%13%21%16%4
1972
16th to endDay
39%6%11%18%18%5%
2121
May1st to 15thDay
34%7%12%22%17%6%
2174
16th to endDay
50%8%13%17%8%
2435
June1st to 15thDay
62%10%14%9%2
2340
16th to endDay
58%12%18%9%1
2340
July1st to 15thDay
58%15%20%5%
2201
16th to endDay
55%13%22%8%
2310
August1st to 15thDay
52%14%23%9%
2285
16th to endDay
57%15%19%7%
2106
September1st to 15thDay
58%16%17%7%
1980
16th to endDay
63%12%13%8%2
1980
October1st to 15thDay
47%10%12%14%11%2
1896
16th to endDay
47%6%7%14%14%9%
1920
November1st to 15thDay
34%5%10%21%20%7%
1907
16th to endDay
38%6%10%15%19%9%
1950
December1st to 15thDay
38%5%11%19%18%6%
1806
16th to endDay
32%6%13%25%17%4
1872
January1st to 15thNight
36%6%15%23%15%3
2472
16th to endNight
30%5%13%26%17%5%
2430
February1st to 15thNight
32%5%8%24%20%9%
2112
16th to endNight
23%5%14%25%23%7%
1767
March1st to 15thNight
23%6%12%30%20%6%
1980
16th to endNight
25%6%13%28%20%5%
2112
April1st to 15thNight
20%5%17%31%18%5%
1976
16th to endNight
25%6%13%26%23%4
1839
May1st to 15thNight
20%7%16%30%19%5%
1785
16th to endNight
31%10%19%26%11%
1684
June1st to 15thNight
50%11%21%14%2
1620
16th to endNight
39%17%27%13%2
1620
July1st to 15thNight
39%20%29%10%
1530
16th to endNight
34%16%34%13%
1595
August1st to 15thNight
37%16%30%14%
1639
16th to endNight
41%18%28%10%1
2092
September1st to 15thNight
42%16%29%10%1
1980
16th to endNight
48%16%21%10%3
1980
October1st to 15thNight
34%10%20%18%14%2
2063
16th to endNight
40%6%12%17%16%7%
2304
November1st to 15thNight
28%410%26%22%7%
2281
16th to endNight
34%6%9%20%20%9%
2340
December1st to 15thNight
30%6%14%23%19%5%
2481
16th to endNight
26%5%15%28%19%3
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
17%8%29%28%14%1
123
16th to endDay
14%9%27%28%16%4
96
February1st to 15thDay
7%5%21%30%23%12%
90
16th to endDay
8%122%38%27%2
207
March1st to 15thDay
420%38%30%5%
270
16th to endDay
5%218%31%35%6%
288
April1st to 15thDay
4218%27%36%10%
270
16th to endDay
7%10%30%37%14%
270
May1st to 15thDay
47%20%40%26%
288
16th to endDay
7%15%16%31%38%
331
June1st to 15thDay
19%1311%25%37%
315
16th to endDay
6%127%20%62%
315
July1st to 15thDay
7%319%68%
305
16th to endDay
7%16%20%63%
326
August1st to 15thDay
6%1322%65%
313
16th to endDay
13%137%20%54%
332
September1st to 15thDay
8%137%19%60%
315
16th to endDay
12%8%28%48%
314
October1st to 15thDay
6%17%21%41%20%
315
16th to endDay
11%216%29%26%13%
336
November1st to 15thDay
6%19%32%35%14%
325
16th to endDay
5%118%37%31%5%
330
December1st to 15thDay
16%317%26%30%6%
186
16th to endDay
29%29%39%18%
144
January1st to 15thNight
9%5%19%41%23%1
765
16th to endNight
7%326%45%16%
768
February1st to 15thNight
10%324%45%15%
704
16th to endNight
5%323%51%15%
631
March1st to 15thNight
5%225%45%20%
720
16th to endNight
5%320%50%19%
768
April1st to 15thNight
4216%50%25%1
718
16th to endNight
6%117%47%26%
720
May1st to 15thNight
319%48%33%4
705
16th to endNight
6%15%30%46%10%
563
June1st to 15thNight
12%317%44%21%
540
16th to endNight
5%19%47%35%
540
July1st to 15thNight
5%115%44%41%
510
16th to endNight
41341%48%
564
August1st to 15thNight
7%5%44%41%
569
16th to endNight
10%310%42%32%
764
September1st to 15thNight
8%149%41%34%
720
16th to endNight
13%1315%43%23%
717
October1st to 15thNight
9%5%34%40%9%
720
16th to endNight
14%111%34%30%7%
768
November1st to 15thNight
6%15%42%31%3
760
16th to endNight
10%117%43%24%2
780
December1st to 15thNight
7%217%41%30%1
780
16th to endNight
5%115%39%33%3
832
Page generated at 2018-01-12 22:01:32. Version ac04

Copyright 2018 A. Danko


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