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 2005-11-06 to 2024-02-25.

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
32%
23547
9%
80889
8%
23456
35%
23456
12%
63129

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 10thNight
11%
939
1%
4719
0%
926
12%
926
2%
4411
January11th to 20thNight
12%
916
1%
4397
1%
900
13%
900
2%
4168
January21st to endNight
18%
828
2%
4519
3%
814
19%
814
3%
4013
February1st to 10thNight
16%
760
5%
2470
2%
760
19%
760
5%
2155
February11th to 20thNight
19%
740
7%
2405
4%
740
23%
740
8%
1978
February21st to endNight
20%
611
8%
1865
2%
611
26%
611
11%
1490
March1st to 10thNight
26%
720
12%
2047
7%
720
31%
720
17%
1545
March11th to 20thNight
26%
720
17%
1980
9%
720
33%
720
18%
1469
March21st to endNight
34%
792
16%
2178
8%
792
40%
792
21%
1580
April1st to 10thNight
29%
720
13%
1897
6%
720
34%
720
19%
1407
April11th to 20thNight
38%
533
20%
1597
11%
533
43%
533
23%
1068
April21st to endNight
34%
540
15%
1620
9%
540
39%
540
18%
1172
May1st to 10thNight
43%
540
15%
1620
12%
540
47%
540
23%
1084
May11th to 20thNight
50%
440
19%
1502
18%
440
57%
440
23%
937
May21st to endNight
55%
388
15%
1551
17%
388
61%
388
24%
887
June1st to 10thNight
47%
360
14%
1292
14%
360
52%
360
22%
804
June11th to 20thNight
56%
360
16%
1260
17%
360
61%
360
28%
737
June21st to endNight
55%
360
15%
1260
17%
360
58%
360
25%
787
July1st to 10thNight
66%
350
19%
1225
23%
350
69%
350
35%
652
July11th to 20thNight
60%
392
18%
1262
21%
392
63%
392
30%
751
July21st to endNight
63%
591
15%
1663
15%
558
63%
558
31%
1020
August1st to 10thNight
61%
537
17%
1600
13%
534
65%
534
33%
956
August11th to 20thNight
63%
534
19%
1598
14%
534
66%
534
31%
961
August21st to endNight
53%
594
17%
1782
12%
594
56%
594
27%
1143
September1st to 10thNight
57%
710
17%
1814
10%
710
59%
710
33%
1173
September11th to 20thNight
56%
720
20%
1980
15%
720
58%
720
30%
1286
September21st to endNight
45%
720
16%
1980
13%
720
47%
720
21%
1426
October1st to 10thNight
39%
720
13%
2131
11%
720
42%
720
18%
1566
October11th to 20thNight
26%
720
8%
2160
5%
720
30%
720
11%
1739
October21st to endNight
20%
792
8%
2450
6%
792
23%
792
8%
2048
November1st to 10thNight
25%
740
11%
2443
10%
740
29%
740
11%
1895
November11th to 20thNight
19%
760
7%
2660
6%
760
21%
760
7%
2190
November21st to endNight
13%
760
4%
2660
3%
760
15%
760
5%
2318
December1st to 10thNight
10%
760
1%
2660
1%
760
11%
760
2%
2467
December11th to 20thNight
9%
843
1%
3412
0%
842
11%
842
2%
3047
December21st to endNight
7%
1037
1%
5230
0%
1026
8%
1026
1%
4799

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%11%5%8%6%35%45%6%31%
78213
Night
17%14%6%10%7%34445%25%
81082
TransparencyDay
54%7%12%17%9%1
77919
Night
61%7%10%14%7%1
80911
SeeingDay
19%10%26%27%14%4
14149
Night
22%11%27%27%12%2
23582

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 10thDay
16%23%15%15%9%35%4236%
2222
11th to 20thDay
11%20%10%25%13%444325%
2569
21st to endDay
19%20%10%14%8%45%4439%
3124
February1st to 10thDay
14%20%8%17%11%4443411%
1710
11th to 20thDay
12%14%8%13%9%46%6%46%17%
1663
21st to endDay
15%16%7%11%6%46%5%5%5%20%
1482
March1st to 10thDay
14%11%48%8%45%5%5%7%30%
1909
11th to 20thDay
13%11%5%8%7%45%5%5%6%30%
1980
21st to endDay
17%8%46%6%4445%6%35%
2178
April1st to 10thDay
20%10%47%5%3445%7%30%
2075
11th to 20thDay
18%9%36%5%34446%39%
2312
21st to endDay
20%8%46%425%45%7%34%
2340
May1st to 10thDay
17%7%26%5%345%5%8%38%
2340
11th to 20thDay
16%7%25%435%446%43%
2392
21st to endDay
11%5%25%5%3445%8%46%
2725
June1st to 10thDay
13%7%35%5%35%6%6%8%41%
2664
11th to 20thDay
12%5%25%5%35%5%5%9%43%
2700
21st to endDay
14%6%245%345%5%8%43%
2700
July1st to 10thDay
9%4244345%7%9%50%
2700
11th to 20thDay
10%6%25%43446%8%46%
2652
21st to endDay
10%5%345%345%7%9%45%
2552
August1st to 10thDay
11%6%334335%5%10%47%
2327
11th to 20thDay
11%5%245%35%47%8%47%
2303
21st to endDay
13%7%26%435%5%6%9%41%
2566
September1st to 10thDay
13%6%36%5%345%5%8%41%
2134
11th to 20thDay
13%6%35%435%5%5%9%42%
1980
21st to endDay
18%6%37%6%35%46%6%36%
1980
October1st to 10thDay
21%8%37%5%3445%6%33%
1828
11th to 20thDay
26%13%5%8%7%345%45%20%
1800
21st to endDay
30%13%5%9%7%43335%17%
1904
November1st to 10thDay
19%19%5%7%6%35%5%5%6%20%
1634
11th to 20thDay
19%20%7%9%6%35%5%47%16%
1520
21st to endDay
23%24%8%10%7%343449%
1520
December1st to 10thDay
17%29%11%12%7%343337%
1520
11th to 20thDay
19%22%8%15%8%35%3449%
1777
21st to endDay
28%22%8%12%7%243336%
2431
January1st to 10thNight
15%25%12%15%11%343336%
4719
11th to 20thNight
15%18%10%20%13%45%4336%
4397
21st to endNight
17%19%10%13%9%4434411%
4532
February1st to 10thNight
13%18%8%14%12%5%5%5%4413%
2470
11th to 20thNight
14%14%9%15%9%35%345%19%
2403
21st to endNight
15%15%6%10%8%35%5%5%5%21%
1865
March1st to 10thNight
14%11%6%10%7%44346%31%
2037
11th to 20thNight
14%12%6%8%7%34445%32%
1979
21st to endNight
16%11%37%5%35%445%35%
2178
April1st to 10thNight
21%10%46%6%34446%31%
1897
11th to 20thNight
18%9%36%33445%7%38%
1597
21st to endNight
20%9%47%6%3445%5%32%
1620
May1st to 10thNight
15%6%38%6%25%45%8%38%
1620
11th to 20thNight
14%7%36%6%3446%6%41%
1501
21st to endNight
10%5%26%5%35%5%6%7%46%
1550
June1st to 10thNight
13%6%26%7%45%45%7%40%
1292
11th to 20thNight
11%5%245%35%5%7%10%43%
1260
21st to endNight
14%7%26%5%345%6%8%41%
1260
July1st to 10thNight
9%43442345%9%53%
1260
11th to 20thNight
9%425%5%45%48%9%45%
1304
21st to endNight
8%5%245%45%5%7%7%48%
1761
August1st to 10thNight
10%425%42445%9%49%
1611
11th to 20thNight
9%436%5%35%5%6%8%47%
1598
21st to endNight
12%7%36%6%35%45%9%42%
1782
September1st to 10thNight
11%425%435%6%7%9%44%
1814
11th to 20thNight
12%5%25%5%345%5%8%45%
1980
21st to endNight
17%7%37%7%35%45%6%36%
1980
October1st to 10thNight
20%9%36%6%35%5%5%7%32%
2131
11th to 20thNight
27%12%48%6%345%5%6%21%
2160
21st to endNight
29%13%49%7%34446%18%
2450
November1st to 10thNight
20%16%5%7%6%35%45%6%24%
2443
11th to 20thNight
20%18%6%9%7%44446%16%
2660
21st to endNight
25%23%7%8%6%34445%12%
2660
December1st to 10thNight
21%26%11%12%6%343437%
2660
11th to 20thNight
17%23%8%15%8%35%44410%
3415
21st to endNight
25%21%10%14%7%343337%
5236

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 10thDay
84%7%6%3
2223
11th to 20thDay
87%5%421
2569
21st to endDay
79%9%6%31
3124
February1st to 10thDay
77%7%7%8%1
1710
11th to 20thDay
67%10%11%8%4
1672
21st to endDay
65%7%11%12%4
1482
March1st to 10thDay
55%7%13%16%7%1
1912
11th to 20thDay
53%8%11%17%9%2
1980
21st to endDay
50%5%12%19%12%2
2178
April1st to 10thDay
54%6%12%17%10%
2075
11th to 20thDay
48%49%22%16%2
2312
21st to endDay
48%7%13%19%11%3
2340
May1st to 10thDay
44%6%10%24%13%3
2340
11th to 20thDay
43%7%9%23%17%2
2396
21st to endDay
35%8%15%23%15%3
2725
June1st to 10thDay
39%9%12%23%16%1
2664
11th to 20thDay
37%6%13%25%18%1
2700
21st to endDay
38%8%14%23%15%2
2700
July1st to 10thDay
29%9%15%26%19%2
2626
11th to 20thDay
34%7%16%30%12%2
2571
21st to endDay
35%8%15%26%15%1
2410
August1st to 10thDay
32%9%17%27%13%2
2314
11th to 20thDay
35%8%17%27%13%
2303
21st to endDay
39%8%15%24%12%1
2566
September1st to 10thDay
40%8%14%25%13%1
2134
11th to 20thDay
38%8%15%28%10%
1980
21st to endDay
48%9%13%23%7%
1980
October1st to 10thDay
52%7%12%19%9%1
1828
11th to 20thDay
65%7%12%11%5%1
1800
21st to endDay
71%5%9%11%3
1904
November1st to 10thDay
65%5%12%13%5%
1634
11th to 20thDay
68%9%11%7%5%
1520
21st to endDay
78%7%9%5%
1520
December1st to 10thDay
84%7%5%21
1520
11th to 20thDay
80%7%9%4
1776
21st to endDay
84%5%8%3
2431
January1st to 10thNight
84%7%6%3
4719
11th to 20thNight
86%6%5%21
4397
21st to endNight
76%10%9%41
4532
February1st to 10thNight
75%7%8%8%2
2470
11th to 20thNight
68%7%10%11%4
2405
21st to endNight
63%7%12%11%6%
1865
March1st to 10thNight
55%6%12%16%9%1
2047
11th to 20thNight
54%6%9%18%11%2
1980
21st to endNight
51%6%10%19%13%2
2178
April1st to 10thNight
54%5%10%20%10%1
1897
11th to 20thNight
45%5%9%21%19%1
1597
21st to endNight
53%6%9%16%14%2
1620
May1st to 10thNight
45%6%10%20%16%2
1620
11th to 20thNight
43%5%8%22%19%3
1502
21st to endNight
36%8%14%23%16%4
1551
June1st to 10thNight
42%7%10%22%18%2
1292
11th to 20thNight
36%6%13%25%19%2
1260
21st to endNight
40%7%12%25%14%2
1260
July1st to 10thNight
28%6%12%28%22%4
1225
11th to 20thNight
32%9%13%29%16%1
1262
21st to endNight
33%9%14%26%17%1
1663
August1st to 10thNight
32%7%18%26%14%2
1600
11th to 20thNight
33%8%17%25%16%2
1598
21st to endNight
40%7%15%25%12%1
1782
September1st to 10thNight
34%9%14%28%14%2
1814
11th to 20thNight
37%8%15%28%12%
1980
21st to endNight
48%8%13%22%8%
1980
October1st to 10thNight
52%8%10%19%10%1
2131
11th to 20thNight
63%8%11%14%4
2160
21st to endNight
69%7%9%10%5%
2450
November1st to 10thNight
61%7%11%17%4
2443
11th to 20thNight
68%7%13%8%31
2660
21st to endNight
73%9%11%6%1
2660
December1st to 10thNight
83%7%6%31
2660
11th to 20thNight
78%9%9%4
3415
21st to endNight
84%5%8%2
5236

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 10thDay
25%19%32%19%42
186
11th to 20thDay
20%16%39%19%6%
270
21st to endDay
28%13%30%22%7%
297
February1st to 10thDay
22%23%34%17%3
270
11th to 20thDay
23%17%39%20%2
270
21st to endDay
21%27%36%15%
210
March1st to 10thDay
21%13%37%21%7%1
352
11th to 20thDay
20%14%32%26%7%1
420
21st to endDay
24%12%29%27%7%2
462
April1st to 10thDay
21%12%32%24%11%
420
11th to 20thDay
24%12%29%17%11%6%
412
21st to endDay
25%8%28%26%11%1
420
May1st to 10thDay
21%7%27%29%13%2
423
11th to 20thDay
17%7%24%32%17%3
447
21st to endDay
12%6%24%30%23%6%
485
June1st to 10thDay
12%5%27%36%17%3
594
11th to 20thDay
13%6%24%36%18%4
630
21st to endDay
15%425%35%16%3
630
July1st to 10thDay
9%321%35%27%4
621
11th to 20thDay
11%5%22%34%20%7%
618
21st to endDay
12%419%39%20%6%
493
August1st to 10thDay
14%419%33%21%9%
446
11th to 20thDay
13%412%38%24%9%
439
21st to endDay
16%6%20%29%21%7%
495
September1st to 10thDay
14%6%22%33%19%7%
450
11th to 20thDay
11%6%22%26%25%9%
450
21st to endDay
17%10%22%25%20%6%
450
October1st to 10thDay
21%12%24%24%15%4
450
11th to 20thDay
26%17%30%22%41
450
21st to endDay
32%16%29%17%5%
419
November1st to 10thDay
30%16%27%19%8%
252
11th to 20thDay
30%19%28%18%32
180
21st to endDay
28%22%34%14%2
180
December1st to 10thDay
30%19%31%17%4
180
11th to 20thDay
29%22%29%16%4
180
21st to endDay
34%21%35%8%21
198
January1st to 10thNight
24%18%31%21%5%1
950
11th to 20thNight
28%15%31%20%6%1
920
21st to endNight
21%10%33%27%8%1
836
February1st to 10thNight
21%16%36%22%4
760
11th to 20thNight
19%12%36%26%6%1
743
21st to endNight
22%15%35%24%5%
611
March1st to 10thNight
19%11%36%27%8%
720
11th to 20thNight
19%13%34%24%8%1
720
21st to endNight
21%8%29%29%12%1
792
April1st to 10thNight
23%11%29%29%7%1
720
11th to 20thNight
22%9%26%28%13%2
533
21st to endNight
25%6%25%29%14%1
540
May1st to 10thNight
17%423%38%16%2
540
11th to 20thNight
19%319%39%20%1
440
21st to endNight
12%322%39%21%3
389
June1st to 10thNight
15%5%22%38%18%3
360
11th to 20thNight
11%5%23%38%23%1
360
21st to endNight
15%319%36%26%1
360
July1st to 10thNight
10%413%47%24%2
350
11th to 20thNight
10%319%34%30%3
392
21st to endNight
9%318%42%27%1
591
August1st to 10thNight
12%316%36%31%2
537
11th to 20thNight
9%315%34%32%6%
534
21st to endNight
13%5%22%29%28%4
594
September1st to 10thNight
11%6%20%35%21%7%
710
11th to 20thNight
13%5%20%33%22%6%
720
21st to endNight
18%8%22%26%20%6%
720
October1st to 10thNight
22%9%24%28%16%2
720
11th to 20thNight
30%15%22%23%8%2
720
21st to endNight
33%13%27%22%41
792
November1st to 10thNight
30%13%27%21%8%1
740
11th to 20thNight
27%19%29%17%8%
760
21st to endNight
36%15%29%18%3
760
December1st to 10thNight
33%20%30%12%4
760
11th to 20thNight
25%20%35%16%3
843
21st to endNight
33%14%34%15%3
1045
Page generated at 2024-02-22 06:05:43. Version ac07

Copyright 2024 Attilla Danko


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