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 2017-12-20.

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%
15557
10%
47958
8%
15520
36%
15520
14%
36658

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
8%
896
1%
2616
0%
895
10%
895
3%
2438
January16th to endNight
17%
810
4%
2538
3%
810
18%
810
5%
2273
February1st to 15thNight
16%
701
3%
2287
2%
701
18%
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
37%
659
21%
1283
April16th to endNight
39%
540
17%
1620
10%
540
44%
540
22%
1107
May1st to 15thNight
46%
536
14%
1616
13%
536
49%
536
22%
1091
May16th to endNight
54%
374
15%
1497
15%
374
60%
374
22%
878
June1st to 15thNight
50%
360
12%
1281
12%
360
54%
360
22%
804
June16th to endNight
58%
360
13%
1260
15%
360
62%
360
26%
776
July1st to 15thNight
65%
340
17%
1190
21%
340
69%
340
35%
640
July16th to endNight
62%
535
14%
1502
15%
502
62%
502
29%
938
August1st to 15thNight
61%
539
16%
1609
13%
536
64%
536
31%
982
August16th to endNight
59%
573
18%
1719
14%
573
61%
573
29%
1078
September1st to 15thNight
54%
714
15%
1872
10%
714
56%
714
29%
1260
September16th to endNight
51%
717
18%
1980
14%
717
53%
717
26%
1344
October1st to 15thNight
37%
720
12%
2142
10%
720
40%
720
17%
1601
October16th to endNight
22%
768
7%
2354
4%
768
25%
768
9%
1948
November1st to 15thNight
25%
760
10%
2561
11%
760
28%
760
10%
2006
November16th to endNight
17%
780
5%
2730
4%
780
19%
780
6%
2328
December1st to 15thNight
10%
780
1%
2730
0%
780
11%
780
2%
2539
December16th to endNight
8%
976
2%
2943
0%
976
10%
976
3%
2712

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%
48882
Night
17%12%5%8%6%34445%27%
48128
Cloud CoverDay
16%10%47%5%3445%6%32%
48892
Night
17%12%5%8%6%34446%27%
48132
TransparencyDay
52%7%12%18%9%
48570
Night
58%6%10%15%8%
47958
SeeingDay
20%5%23%29%16%5%
6079
Night
23%8%26%26%13%2
15565

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%46%
2340
16th to endDay
12%6%25%33446%7%42%
2477
September1st to 15thDay
15%6%26%434447%40%
2082
16th to endDay
16%5%26%425%46%7%39%
1980
October1st to 15thDay
22%9%47%5%23345%31%
1818
16th to endDay
33%10%48%5%4333418%
1869
November1st to 15thDay
21%17%5%6%6%35%5%45%19%
1626
16th to endDay
25%20%6%9%6%3424312%
1560
December1st to 15thDay
20%24%10%12%7%343236%
1560
16th to endDay
21%25%8%9%8%25%3346%
1377
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%4245%5%9%46%
1620
16th to endNight
10%5%26%5%34447%45%
1719
September1st to 15thNight
14%4244345%5%8%41%
1872
16th to endNight
14%6%36%6%24346%41%
1980
October1st to 15thNight
23%8%26%5%2445%6%29%
2142
16th to endNight
30%11%37%6%24445%19%
2354
November1st to 15thNight
21%14%47%6%34446%22%
2561
16th to endNight
26%19%6%7%5%34335%14%
2730
December1st to 15thNight
20%25%10%12%5%342327%
2730
16th to endNight
23%22%9%11%7%342337%
2943

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%46%
2340
16th to endDay
13%5%35%42446%7%42%
2477
September1st to 15thDay
15%6%35%434447%40%
2082
16th to endDay
17%5%25%5%3436%7%38%
1980
October1st to 15thDay
22%9%37%5%24435%31%
1818
16th to endDay
31%12%5%7%5%3333418%
1869
November1st to 15thDay
21%15%5%7%6%245%45%20%
1626
16th to endDay
23%20%6%8%5%3443413%
1560
December1st to 15thDay
19%24%9%13%7%243346%
1560
16th to endDay
20%24%9%12%6%333347%
1377
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
10%4344335%6%9%45%
1620
16th to endNight
10%5%26%5%33447%46%
1719
September1st to 15thNight
13%5%26%3245%6%7%43%
1872
16th to endNight
13%6%35%5%33446%42%
1980
October1st to 15thNight
21%8%36%5%2445%6%30%
2142
16th to endNight
28%11%37%6%24436%20%
2354
November1st to 15thNight
20%14%47%6%35%445%23%
2561
16th to endNight
24%18%5%7%5%24345%16%
2730
December1st to 15thNight
19%24%9%12%6%243338%
2730
16th to endNight
22%22%9%11%7%343239%
2943

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
2327
16th to endDay
39%7%15%24%11%1
2477
September1st to 15thDay
43%7%13%24%10%
2082
16th to endDay
43%8%13%26%8%
1980
October1st to 15thDay
55%5%10%18%8%
1818
16th to endDay
70%5%10%10%3
1869
November1st to 15thDay
65%7%10%10%5%
1626
16th to endDay
76%5%10%6%1
1560
December1st to 15thDay
84%6%5%2
1560
16th to endDay
83%5%7%3
1377
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
34%7%17%24%14%1
1609
16th to endNight
37%6%14%26%13%1
1719
September1st to 15thNight
39%7%13%26%11%1
1872
16th to endNight
42%7%14%25%9%
1980
October1st to 15thNight
54%6%9%18%9%
2142
16th to endNight
67%7%11%10%3
2354
November1st to 15thNight
63%5%12%12%31
2561
16th to endNight
72%6%12%6%
2730
December1st to 15thNight
82%7%6%2
2730
16th to endNight
82%5%7%3
2943

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%34%26%11%
313
16th to endDay
20%213%29%23%11%
332
September1st to 15thDay
15%218%28%21%13%
315
16th to endDay
17%419%22%26%9%
314
October1st to 15thDay
21%7%27%26%11%4
315
16th to endDay
35%10%25%22%4
285
November1st to 15thDay
32%7%27%22%7%1
114
16th to endDay
30%14%33%18%3
90
December1st to 15thDay
28%17%33%15%4
90
16th to endDay
44%23%25%6%
72
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%215%36%30%4
539
16th to endNight
12%318%31%30%5%
573
September1st to 15thNight
15%420%30%19%9%
714
16th to endNight
16%5%18%28%23%7%
717
October1st to 15thNight
25%8%22%27%13%3
720
16th to endNight
35%11%25%22%4
768
November1st to 15thNight
28%12%28%20%10%1
760
16th to endNight
36%14%24%19%5%
780
December1st to 15thNight
32%19%31%13%3
780
16th to endNight
33%14%33%15%3
976
Page generated at 2017-12-21 07:04:55. Version ac04

Copyright 2017 A. Danko


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