ES Fox Observatory (BAS/BOEC)
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the ES Fox Observatory (BAS/BOEC) clear sky chart from 2005-11-05 to 2017-08-12.

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
33%
15049
10%
46390
8%
15012
36%
15012
14%
35444

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
10%
896
1%
2616
0%
895
11%
895
3%
2438
January16th to endNight
17%
810
4%
2538
3%
810
18%
810
5%
2273
February1st to 15thNight
17%
701
3%
2287
2%
701
19%
701
5%
1986
February16th to endNight
24%
631
8%
1973
3%
631
29%
631
10%
1595
March1st to 15thNight
25%
720
11%
2025
6%
720
29%
720
15%
1571
March16th to endNight
39%
768
19%
2112
12%
768
44%
768
23%
1480
April1st to 15thNight
32%
659
15%
1801
7%
659
38%
659
21%
1283
April16th to endNight
39%
540
17%
1620
10%
540
44%
540
22%
1107
May1st to 15thNight
47%
536
14%
1616
13%
536
50%
536
22%
1091
May16th to endNight
54%
374
15%
1497
15%
374
61%
374
22%
878
June1st to 15thNight
51%
360
12%
1281
13%
360
55%
360
22%
804
June16th to endNight
58%
360
13%
1260
15%
360
61%
360
26%
776
July1st to 15thNight
66%
340
17%
1190
21%
340
69%
340
35%
640
July16th to endNight
62%
535
14%
1502
15%
502
63%
502
29%
938
August1st to 15thNight
60%
527
16%
1575
13%
524
64%
524
31%
958
August16th to endNight
58%
525
18%
1575
14%
525
61%
525
29%
984
September1st to 15thNight
54%
654
15%
1715
10%
654
56%
654
28%
1169
September16th to endNight
50%
657
17%
1815
12%
657
52%
657
25%
1242
October1st to 15thNight
36%
660
12%
1963
11%
660
40%
660
16%
1474
October16th to endNight
22%
704
6%
2158
4%
704
25%
704
9%
1800
November1st to 15thNight
26%
700
11%
2359
12%
700
29%
700
11%
1822
November16th to endNight
19%
720
5%
2520
4%
720
21%
720
6%
2147
December1st to 15thNight
11%
720
1%
2520
0%
720
11%
720
2%
2342
December16th to endNight
8%
952
2%
2872
0%
952
10%
952
3%
2646

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
16%10%47%5%34446%32%
47582
Night
17%12%5%8%6%34445%27%
46560
Cloud CoverDay
16%10%47%5%3445%6%32%
47592
Night
17%12%5%8%6%34446%27%
46564
TransparencyDay
52%7%12%18%9%
47270
Night
58%6%10%15%8%
46390
SeeingDay
20%5%23%29%16%5%
5653
Night
22%8%26%26%13%2
15057

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%18%11%14%9%343337%
1322
16th to endDay
15%19%9%15%9%4444310%
1685
February1st to 15thDay
13%18%8%15%9%445%3412%
1575
16th to endDay
15%16%7%9%6%47%5%4418%
1497
March1st to 15thDay
15%10%48%6%35%5%5%6%29%
1924
16th to endDay
14%7%46%6%3445%7%35%
2112
April1st to 15thDay
21%9%35%423347%34%
2155
16th to endDay
19%7%25%414447%38%
2340
May1st to 15thDay
17%7%24433447%40%
2334
16th to endDay
11%5%14434448%45%
2618
June1st to 15thDay
12%6%35%4246%5%8%39%
2676
16th to endDay
12%5%25%5%35%5%5%9%40%
2700
July1st to 15thDay
9%4244245%6%8%46%
2700
16th to endDay
9%4244245%6%10%45%
2555
August1st to 15thDay
10%5%2342445%9%47%
2288
16th to endDay
11%6%25%43446%7%43%
2270
September1st to 15thDay
16%6%35%434447%38%
1909
16th to endDay
17%5%25%42436%7%38%
1815
October1st to 15thDay
21%9%47%5%23345%31%
1667
16th to endDay
34%10%5%8%5%33335%16%
1713
November1st to 15thDay
21%16%46%6%35%5%45%20%
1498
16th to endDay
25%20%7%9%6%3423412%
1440
December1st to 15thDay
21%24%10%12%7%343236%
1440
16th to endDay
21%25%9%9%8%243345%
1349
January1st to 15thNight
21%20%9%13%8%35%3337%
2616
16th to endNight
16%16%10%15%9%36%33410%
2538
February1st to 15thNight
14%18%9%12%9%4443413%
2285
16th to endNight
15%13%7%12%8%35%345%20%
1973
March1st to 15thNight
16%11%6%8%6%24346%27%
2013
16th to endNight
15%8%46%5%24335%39%
2112
April1st to 15thNight
21%8%35%423446%34%
1801
16th to endNight
19%7%25%42435%6%37%
1620
May1st to 15thNight
15%7%36%6%24447%36%
1616
16th to endNight
11%5%15%5%35%5%5%7%43%
1495
June1st to 15thNight
13%6%25%6%3445%8%38%
1281
16th to endNight
10%5%26%5%345%6%8%42%
1260
July1st to 15thNight
9%32442346%9%50%
1260
16th to endNight
7%413445%6%7%7%46%
1607
August1st to 15thNight
9%425%42445%9%46%
1586
16th to endNight
10%5%26%5%23447%46%
1575
September1st to 15thNight
14%5%25%3345%5%7%40%
1715
16th to endNight
15%7%36%5%24346%40%
1815
October1st to 15thNight
22%9%36%5%2445%6%29%
1963
16th to endNight
30%11%37%6%24446%18%
2158
November1st to 15thNight
20%14%5%7%6%34446%23%
2359
16th to endNight
26%19%6%7%5%3434414%
2520
December1st to 15thNight
21%25%9%12%5%343327%
2520
16th to endNight
23%22%9%11%7%342337%
2872

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
19%18%10%16%8%343337%
1322
16th to endDay
14%19%9%14%10%45%33410%
1685
February1st to 15thDay
13%18%8%14%9%45%44412%
1575
16th to endDay
15%17%6%9%7%37%5%45%17%
1497
March1st to 15thDay
14%10%49%6%35%5%5%5%29%
1935
16th to endDay
14%7%46%6%345%46%35%
2111
April1st to 15thDay
21%10%26%423346%33%
2155
16th to endDay
19%7%35%42335%6%39%
2340
May1st to 15thDay
18%6%24424437%40%
2334
16th to endDay
12%5%2443445%8%45%
2618
June1st to 15thDay
12%6%244345%5%9%39%
2676
16th to endDay
12%5%24435%46%8%40%
2700
July1st to 15thDay
10%42442447%7%47%
2700
16th to endDay
9%4244235%7%9%44%
2555
August1st to 15thDay
11%5%1433445%8%47%
2288
16th to endDay
12%5%35%43446%8%42%
2270
September1st to 15thDay
16%6%35%434447%38%
1909
16th to endDay
18%6%25%5%3436%7%37%
1815
October1st to 15thDay
22%9%37%5%24335%31%
1667
16th to endDay
32%12%5%7%5%3333416%
1713
November1st to 15thDay
20%15%5%7%6%25%5%46%21%
1498
16th to endDay
24%20%6%8%6%345%3313%
1440
December1st to 15thDay
20%24%9%13%7%243346%
1440
16th to endDay
20%24%9%12%6%343347%
1349
January1st to 15thNight
21%18%8%13%9%344437%
2616
16th to endNight
15%18%8%14%8%35%44411%
2538
February1st to 15thNight
14%17%9%11%9%45%34414%
2278
16th to endNight
16%12%7%11%7%35%346%20%
1973
March1st to 15thNight
15%12%5%8%7%34445%27%
2025
16th to endNight
15%8%47%42333440%
2112
April1st to 15thNight
20%9%35%41435%7%34%
1801
16th to endNight
19%7%25%5%2345%6%37%
1620
May1st to 15thNight
15%6%46%6%34447%36%
1615
16th to endNight
11%5%26%435%5%5%7%43%
1495
June1st to 15thNight
13%6%25%5%35%45%8%39%
1281
16th to endNight
11%5%246%245%6%8%42%
1260
July1st to 15thNight
9%41332435%9%51%
1260
16th to endNight
7%4135%36%5%6%7%46%
1607
August1st to 15thNight
9%4344335%6%9%45%
1586
16th to endNight
10%5%26%5%33447%46%
1575
September1st to 15thNight
13%5%26%3245%6%7%41%
1715
16th to endNight
14%6%35%6%33436%41%
1815
October1st to 15thNight
21%8%37%6%2445%6%30%
1963
16th to endNight
28%11%37%6%34335%20%
2158
November1st to 15thNight
19%13%47%6%35%445%24%
2359
16th to endNight
24%18%6%7%5%24345%16%
2520
December1st to 15thNight
20%24%9%12%6%243338%
2520
16th to endNight
22%22%9%12%7%343239%
2872

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
83%5%6%4
1323
16th to endDay
79%6%6%42
1685
February1st to 15thDay
75%6%8%7%
1577
16th to endDay
67%8%10%9%4
1497
March1st to 15thDay
55%7%12%17%7%
1935
16th to endDay
47%6%13%17%13%1
2112
April1st to 15thDay
51%5%9%20%11%
2155
16th to endDay
45%5%10%21%13%2
2340
May1st to 15thDay
44%6%9%23%14%2
2334
16th to endDay
36%7%14%24%15%1
2622
June1st to 15thDay
40%7%13%23%13%
2676
16th to endDay
39%8%15%22%13%
2700
July1st to 15thDay
32%7%15%26%16%2
2541
16th to endDay
34%8%16%27%13%
2397
August1st to 15thDay
34%8%16%25%14%1
2275
16th to endDay
39%7%15%25%11%1
2270
September1st to 15thDay
44%7%14%24%9%
1909
16th to endDay
44%8%14%24%8%
1815
October1st to 15thDay
56%5%10%17%8%
1667
16th to endDay
72%5%10%9%2
1713
November1st to 15thDay
64%7%10%11%5%
1498
16th to endDay
76%5%9%6%1
1440
December1st to 15thDay
84%6%5%2
1440
16th to endDay
83%5%6%3
1349
January1st to 15thNight
82%7%6%31
2616
16th to endNight
77%6%8%5%1
2538
February1st to 15thNight
75%6%9%8%1
2287
16th to endNight
65%6%11%10%5%
1973
March1st to 15thNight
58%6%11%16%6%
2025
16th to endNight
48%410%19%15%2
2112
April1st to 15thNight
50%410%21%12%1
1801
16th to endNight
47%5%9%17%18%2
1620
May1st to 15thNight
46%5%9%20%15%1
1616
16th to endNight
38%6%12%24%15%2
1497
June1st to 15thNight
42%6%12%23%15%1
1281
16th to endNight
38%6%12%26%15%
1260
July1st to 15thNight
29%5%13%28%20%2
1190
16th to endNight
34%9%13%24%16%1
1502
August1st to 15thNight
33%7%17%24%14%1
1575
16th to endNight
37%6%13%27%13%1
1575
September1st to 15thNight
40%8%13%26%10%
1715
16th to endNight
44%6%14%24%10%
1815
October1st to 15thNight
55%6%9%17%9%
1963
16th to endNight
68%6%11%9%3
2158
November1st to 15thNight
62%5%13%13%41
2359
16th to endNight
72%6%12%7%
2520
December1st to 15thNight
82%7%6%2
2520
16th to endNight
83%5%7%3
2872

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%14%36%21%4
71
16th to endDay
34%5%31%23%5%
96
February1st to 15thDay
30%15%35%18%
90
16th to endDay
24%19%29%24%1
81
March1st to 15thDay
22%11%28%29%6%1
225
16th to endDay
23%6%23%30%11%3
288
April1st to 15thDay
25%6%29%25%9%2
270
16th to endDay
27%424%22%15%5%
270
May1st to 15thDay
23%322%28%16%5%
288
16th to endDay
15%324%29%21%5%
331
June1st to 15thDay
14%323%33%20%4
471
16th to endDay
15%225%33%19%3
495
July1st to 15thDay
12%218%37%22%6%
475
16th to endDay
12%119%36%22%7%
388
August1st to 15thDay
15%111%33%26%11%
297
16th to endDay
20%111%31%23%11%
268
September1st to 15thDay
15%320%28%20%11%
255
16th to endDay
19%420%24%22%9%
254
October1st to 15thDay
20%7%27%29%11%3
255
16th to endDay
39%9%24%20%5%
225
November1st to 15thDay
27%6%25%27%10%2
76
16th to endDay
30%13%31%21%3
60
December1st to 15thDay
31%20%28%15%5%
60
16th to endDay
43%26%25%4
64
January1st to 15thNight
27%17%32%17%4
900
16th to endNight
23%10%33%24%6%1
810
February1st to 15thNight
23%11%35%23%5%
704
16th to endNight
21%9%32%28%8%
631
March1st to 15thNight
22%9%35%23%8%
720
16th to endNight
19%5%28%29%14%2
768
April1st to 15thNight
23%9%29%28%7%1
659
16th to endNight
24%424%27%16%1
540
May1st to 15thNight
19%319%36%18%2
536
16th to endNight
14%222%35%23%2
375
June1st to 15thNight
14%421%36%20%2
360
16th to endNight
13%217%39%27%
360
July1st to 15thNight
11%215%40%27%3
340
16th to endNight
9%118%38%28%2
535
August1st to 15thNight
11%216%36%29%4
527
16th to endNight
12%317%31%30%4
525
September1st to 15thNight
16%420%31%18%8%
654
16th to endNight
17%5%19%29%21%6%
657
October1st to 15thNight
25%9%22%26%13%2
660
16th to endNight
36%11%25%22%4
704
November1st to 15thNight
26%12%28%20%10%1
700
16th to endNight
35%13%24%20%5%
720
December1st to 15thNight
33%19%29%13%3
720
16th to endNight
32%13%33%15%3
952
Page generated at 2017-08-13 14:16:55. Version ac04

Copyright 2017 A. Danko


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