Eustis Ridge Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Eustis Ridge Observatory clear sky chart from 2005-11-06 to 2024-01-27.

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
28%
22907
13%
75068
7%
22862
36%
22862
14%
53392

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
15%
760
12%
2649
3%
757
26%
757
9%
1956
January11th to 20thNight
18%
760
10%
2660
3%
760
26%
760
6%
2062
January21st to endNight
16%
820
13%
2868
4%
820
28%
820
10%
2027
February1st to 10thNight
14%
720
11%
2434
3%
720
25%
720
9%
1801
February11th to 20thNight
14%
703
13%
2104
2%
700
26%
700
9%
1577
February21st to endNight
15%
592
17%
1776
3%
592
32%
592
12%
1299
March1st to 10thNight
18%
720
15%
2160
6%
720
29%
720
11%
1610
March11th to 20thNight
22%
720
13%
2039
4%
720
30%
720
12%
1507
March21st to endNight
25%
792
18%
2093
6%
792
34%
792
16%
1535
April1st to 10thNight
22%
720
13%
1800
4%
720
27%
720
15%
1388
April11th to 20thNight
30%
619
16%
1683
6%
619
36%
619
20%
1172
April21st to endNight
24%
540
13%
1620
5%
540
31%
540
14%
1184
May1st to 10thNight
30%
540
13%
1620
9%
540
35%
540
17%
1168
May11th to 20thNight
30%
432
15%
1494
10%
432
41%
432
16%
1046
May21st to endNight
41%
389
11%
1551
12%
388
49%
388
16%
1036
June1st to 10thNight
33%
360
10%
1332
9%
360
42%
360
15%
936
June11th to 20thNight
41%
360
12%
1260
13%
360
47%
360
19%
812
June21st to endNight
43%
360
9%
1339
9%
360
48%
360
17%
914
July1st to 10thNight
45%
350
11%
1400
15%
350
51%
350
19%
871
July11th to 20thNight
50%
348
13%
1392
17%
348
54%
348
20%
858
July21st to endNight
55%
394
12%
1486
14%
372
58%
372
18%
964
August1st to 10thNight
51%
438
12%
1502
11%
436
53%
436
22%
950
August11th to 20thNight
47%
532
16%
1596
11%
532
51%
532
23%
1063
August21st to endNight
45%
691
20%
1879
10%
691
49%
691
30%
1205
September1st to 10thNight
49%
720
16%
1818
7%
720
53%
720
34%
1165
September11th to 20thNight
47%
720
18%
1980
12%
720
51%
720
28%
1276
September21st to endNight
43%
720
21%
1980
13%
720
48%
720
26%
1318
October1st to 10thNight
40%
720
17%
1980
10%
720
47%
720
19%
1408
October11th to 20thNight
31%
720
13%
2262
7%
720
39%
720
16%
1606
October21st to endNight
24%
792
11%
2574
6%
792
32%
792
10%
1949
November1st to 10thNight
26%
740
15%
2407
9%
740
35%
740
13%
1720
November11th to 20thNight
24%
760
18%
2470
10%
760
34%
760
12%
1818
November21st to endNight
23%
802
13%
2621
6%
802
32%
802
10%
1949
December1st to 10thNight
17%
850
10%
2850
3%
850
26%
850
8%
2231
December11th to 20thNight
19%
850
11%
3471
4%
848
27%
848
7%
2610
December21st to endNight
12%
853
8%
4918
2%
841
22%
841
4%
3401

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
15%10%48%7%45%5%6%7%30%
74653
Night
14%9%48%7%45%5%6%7%31%
75361
TransparencyDay
52%7%11%18%10%1
74358
Night
51%7%12%19%10%1
75191
SeeingDay
23%16%29%20%8%3
14102
Night
22%15%26%27%9%1
22917

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
11%9%5%12%10%5%7%7%7%7%20%
1517
11th to 20thDay
12%11%5%9%9%5%6%6%5%7%25%
1520
21st to endDay
8%9%5%10%10%46%5%6%6%31%
1632
February1st to 10thDay
10%13%5%10%10%6%6%6%7%6%22%
1525
11th to 20thDay
8%12%6%12%10%5%6%5%5%7%24%
1739
21st to endDay
10%14%410%8%46%6%6%6%25%
1480
March1st to 10thDay
12%11%6%9%7%5%5%46%6%29%
1797
11th to 20thDay
13%11%5%9%7%45%447%33%
1921
21st to endDay
13%12%5%10%7%3445%5%31%
2260
April1st to 10thDay
16%15%5%9%6%34446%27%
2160
11th to 20thDay
15%10%48%7%35%446%34%
2226
21st to endDay
19%14%49%7%34445%27%
2340
May1st to 10thDay
20%13%36%5%4445%6%30%
2340
11th to 20thDay
20%9%48%6%35%445%31%
2414
21st to endDay
14%8%37%6%46%6%6%9%29%
2725
June1st to 10thDay
24%8%37%6%45%5%6%7%25%
2620
11th to 20thDay
17%6%37%6%46%5%6%7%33%
2700
21st to endDay
21%8%48%6%35%5%6%8%26%
2612
July1st to 10thDay
14%8%37%6%45%6%6%8%33%
2520
11th to 20thDay
12%8%36%7%5%6%6%7%10%30%
2520
21st to endDay
14%6%37%8%46%7%7%10%27%
2744
August1st to 10thDay
15%7%26%6%46%6%9%8%31%
2409
11th to 20thDay
13%8%36%7%46%6%7%9%31%
2304
21st to endDay
12%7%36%6%46%6%7%8%37%
2475
September1st to 10thDay
13%5%36%6%346%6%8%41%
2142
11th to 20thDay
13%7%35%5%35%446%45%
1980
21st to endDay
13%8%37%5%35%5%7%7%36%
1980
October1st to 10thDay
17%10%47%5%35%46%7%33%
1980
11th to 20thDay
13%12%47%7%36%46%7%30%
1697
21st to endDay
20%13%6%8%6%35%5%5%5%24%
1782
November1st to 10thDay
13%10%5%8%7%35%5%5%6%31%
1671
11th to 20thDay
15%9%5%11%6%46%6%5%6%27%
1710
21st to endDay
14%11%48%7%445%7%7%29%
1553
December1st to 10thDay
14%16%7%11%9%45%5%45%21%
1330
11th to 20thDay
16%11%5%9%6%35%5%5%6%28%
1668
21st to endDay
18%14%5%8%8%45%5%5%6%22%
2660
January1st to 10thNight
10%11%5%10%8%5%6%6%8%8%23%
2649
11th to 20thNight
10%12%5%11%10%5%6%6%6%8%22%
2660
21st to endNight
8%9%411%8%6%7%6%7%9%27%
2868
February1st to 10thNight
9%11%5%10%8%47%7%7%9%24%
2434
11th to 20thNight
6%10%6%10%9%6%6%6%7%9%25%
2102
21st to endNight
11%11%49%7%46%6%6%6%30%
1776
March1st to 10thNight
10%12%7%9%7%46%5%6%6%28%
2150
11th to 20thNight
12%11%5%8%6%46%5%6%6%31%
2038
21st to endNight
13%10%5%9%6%4445%6%32%
2093
April1st to 10thNight
16%12%48%6%35%6%6%5%28%
1800
11th to 20thNight
16%7%36%6%35%5%6%7%35%
1683
21st to endNight
19%10%38%7%3435%7%30%
1620
May1st to 10thNight
16%12%37%5%35%5%5%7%32%
1620
11th to 20thNight
19%7%37%6%45%5%5%6%34%
1493
21st to endNight
15%6%36%5%46%5%6%7%35%
1550
June1st to 10thNight
22%8%36%6%3446%7%32%
1332
11th to 20thNight
15%9%346%35%5%5%8%38%
1260
21st to endNight
20%6%35%5%35%5%6%9%33%
1339
July1st to 10thNight
12%7%35%6%46%5%6%9%38%
1440
11th to 20thNight
13%5%35%5%45%6%6%9%40%
1440
21st to endNight
13%6%25%5%46%6%6%9%38%
1574
August1st to 10thNight
13%6%35%5%345%6%7%42%
1512
11th to 20thNight
12%6%37%6%35%5%6%8%39%
1596
21st to endNight
12%7%25%43445%8%46%
1879
September1st to 10thNight
11%5%245%35%46%8%47%
1818
11th to 20thNight
13%7%25%5%3445%7%46%
1980
21st to endNight
13%7%35%5%346%6%7%42%
1980
October1st to 10thNight
14%9%36%6%446%5%8%36%
1980
11th to 20thNight
16%10%47%6%45%5%6%7%32%
2262
21st to endNight
20%11%46%5%36%5%7%7%25%
2574
November1st to 10thNight
13%9%5%8%7%35%6%5%7%31%
2407
11th to 20thNight
12%8%5%11%8%45%5%5%8%28%
2470
21st to endNight
13%8%48%8%5%7%6%5%7%28%
2621
December1st to 10thNight
15%12%6%11%8%46%5%6%6%22%
2850
11th to 20thNight
17%10%49%7%45%5%5%7%24%
3531
21st to endNight
19%11%49%7%345%5%6%26%
4980

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
60%7%9%14%8%1
1518
11th to 20thDay
57%8%9%15%9%2
1520
21st to endDay
53%6%10%16%14%3
1632
February1st to 10thDay
60%7%9%13%10%2
1525
11th to 20thDay
59%6%10%12%10%2
1748
21st to endDay
59%49%15%9%4
1480
March1st to 10thDay
55%5%10%17%10%3
1800
11th to 20thDay
52%5%9%17%14%4
1921
21st to endDay
55%5%8%17%12%3
2260
April1st to 10thDay
58%6%9%14%11%3
2160
11th to 20thDay
51%5%9%20%13%1
2226
21st to endDay
60%5%8%15%9%4
2340
May1st to 10thDay
54%5%8%20%11%2
2340
11th to 20thDay
55%5%10%18%11%2
2418
21st to endDay
49%9%14%18%9%1
2725
June1st to 10thDay
56%7%12%18%6%
2620
11th to 20thDay
49%7%12%20%11%1
2700
21st to endDay
55%8%12%17%7%1
2612
July1st to 10thDay
46%9%15%20%10%
2450
11th to 20thDay
46%9%14%24%7%
2445
21st to endDay
48%10%14%20%6%1
2591
August1st to 10thDay
47%9%16%22%6%
2395
11th to 20thDay
47%8%17%19%9%
2304
21st to endDay
42%8%14%22%12%1
2475
September1st to 10thDay
39%8%15%27%10%1
2142
11th to 20thDay
39%412%29%14%2
1980
21st to endDay
43%8%13%23%11%1
1980
October1st to 10thDay
49%6%12%21%12%
1980
11th to 20thDay
51%8%14%20%6%
1697
21st to endDay
61%6%11%12%9%1
1782
November1st to 10thDay
52%6%11%18%11%1
1671
11th to 20thDay
56%8%10%14%10%3
1710
21st to endDay
53%7%15%18%6%1
1553
December1st to 10thDay
65%6%5%14%8%1
1330
11th to 20thDay
57%6%7%15%14%1
1668
21st to endDay
59%10%10%12%8%2
2660
January1st to 10thNight
56%8%10%17%9%1
2649
11th to 20thNight
59%9%10%13%7%2
2660
21st to endNight
52%7%11%17%11%2
2868
February1st to 10thNight
55%8%11%16%8%2
2434
11th to 20thNight
55%7%10%15%10%1
2104
21st to endNight
54%6%9%17%12%3
1776
March1st to 10thNight
55%7%9%17%10%2
2160
11th to 20thNight
53%7%11%14%13%2
2039
21st to endNight
51%6%9%19%12%3
2093
April1st to 10thNight
55%6%9%14%14%1
1800
11th to 20thNight
46%6%12%22%14%1
1683
21st to endNight
54%6%12%15%10%3
1620
May1st to 10thNight
51%7%10%20%11%1
1620
11th to 20thNight
51%6%11%18%13%1
1494
21st to endNight
47%9%14%21%9%1
1551
June1st to 10thNight
52%7%13%18%9%
1332
11th to 20thNight
45%5%14%22%12%2
1260
21st to endNight
49%7%16%20%9%
1339
July1st to 10thNight
41%9%17%23%10%
1400
11th to 20thNight
38%11%16%28%7%
1392
21st to endNight
42%10%17%20%10%
1486
August1st to 10thNight
40%9%19%27%6%
1502
11th to 20thNight
41%10%17%22%9%
1596
21st to endNight
36%7%15%28%13%
1879
September1st to 10thNight
33%7%17%31%11%
1818
11th to 20thNight
38%6%13%28%14%1
1980
21st to endNight
40%7%13%26%12%2
1980
October1st to 10thNight
47%8%10%22%12%1
1980
11th to 20thNight
50%7%15%21%7%1
2262
21st to endNight
58%7%10%15%9%
2574
November1st to 10thNight
52%7%12%19%10%1
2407
11th to 20thNight
54%8%10%17%10%2
2470
21st to endNight
55%8%13%16%7%1
2621
December1st to 10thNight
63%6%10%14%7%1
2850
11th to 20thNight
57%8%8%15%11%
3532
21st to endNight
55%8%13%15%9%1
4980

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
28%22%34%14%21
180
11th to 20thDay
29%20%32%16%31
180
21st to endDay
18%20%40%20%3
188
February1st to 10thDay
28%22%29%19%2
245
11th to 20thDay
27%28%28%14%2
412
21st to endDay
28%23%27%19%3
346
March1st to 10thDay
25%21%35%16%4
420
11th to 20thDay
26%23%30%14%6%1
420
21st to endDay
24%21%27%19%7%2
462
April1st to 10thDay
33%19%27%13%7%2
420
11th to 20thDay
28%22%26%14%7%3
412
21st to endDay
31%18%30%14%5%3
420
May1st to 10thDay
33%17%30%13%6%2
423
11th to 20thDay
25%17%33%17%5%2
447
21st to endDay
21%17%35%18%8%1
485
June1st to 10thDay
27%15%31%19%8%1
550
11th to 20thDay
21%12%28%23%13%2
630
21st to endDay
21%10%32%23%11%3
542
July1st to 10thDay
17%11%35%23%10%3
445
11th to 20thDay
16%10%36%25%10%3
444
21st to endDay
13%10%36%31%8%1
488
August1st to 10thDay
17%9%29%30%10%5%
446
11th to 20thDay
16%10%31%24%13%5%
439
21st to endDay
17%14%26%23%14%5%
495
September1st to 10thDay
14%13%28%24%16%5%
450
11th to 20thDay
20%10%28%18%15%10%
450
21st to endDay
17%14%25%22%15%6%
450
October1st to 10thDay
21%15%25%20%15%4
450
11th to 20thDay
25%16%26%19%11%2
367
21st to endDay
30%18%24%22%5%1
396
November1st to 10thDay
28%17%25%22%8%1
365
11th to 20thDay
26%22%24%17%8%2
370
21st to endDay
30%21%26%17%5%1
307
December1st to 10thDay
23%22%31%18%5%1
180
11th to 20thDay
34%18%34%7%6%1
180
21st to endDay
36%20%26%13%41
198
January1st to 10thNight
22%21%33%21%3
760
11th to 20thNight
22%22%28%23%4
760
21st to endNight
17%23%33%22%41
820
February1st to 10thNight
20%22%33%20%3
720
11th to 20thNight
20%25%31%21%3
703
21st to endNight
23%18%34%22%3
592
March1st to 10thNight
25%17%32%24%2
720
11th to 20thNight
26%19%27%23%6%
720
21st to endNight
23%19%26%24%8%
792
April1st to 10thNight
29%16%27%23%6%
720
11th to 20thNight
21%17%27%28%7%
619
21st to endNight
27%13%28%25%7%
540
May1st to 10thNight
24%11%28%27%9%1
540
11th to 20thNight
23%11%28%31%7%1
432
21st to endNight
17%8%25%36%13%1
389
June1st to 10thNight
26%6%25%33%9%1
360
11th to 20thNight
20%8%22%31%19%
360
21st to endNight
21%6%21%39%13%
360
July1st to 10thNight
15%426%38%16%1
350
11th to 20thNight
16%322%41%16%1
348
21st to endNight
16%218%41%22%1
394
August1st to 10thNight
15%417%42%22%1
438
11th to 20thNight
17%321%37%20%1
532
21st to endNight
15%7%24%32%20%2
691
September1st to 10thNight
13%7%23%37%18%2
720
11th to 20thNight
18%10%20%30%20%3
720
21st to endNight
19%8%25%29%17%2
720
October1st to 10thNight
22%11%19%31%15%1
720
11th to 20thNight
23%16%23%24%12%2
720
21st to endNight
30%16%24%25%5%
792
November1st to 10thNight
23%17%26%25%8%1
740
11th to 20thNight
20%21%26%22%9%2
760
21st to endNight
26%20%23%23%6%2
802
December1st to 10thNight
27%20%28%20%6%
850
11th to 20thNight
27%22%24%22%5%1
850
21st to endNight
30%19%28%19%3
863
Page generated at 2024-01-24 09:37:26. Version ac07

Copyright 2024 Attilla Danko


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