EcoEarth Village
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the EcoEarth Village clear sky chart from 2005-11-05 to 2019-06-24.

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
50%
18042
21%
54019
15%
18002
57%
18002
27%
34307

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
34%
839
24%
2717
13%
836
49%
836
25%
1613
January16th to endNight
36%
896
25%
2912
15%
896
50%
896
27%
1718
February1st to 15thNight
36%
820
24%
2586
14%
820
48%
820
27%
1551
February16th to endNight
29%
735
23%
2205
12%
735
41%
735
25%
1419
March1st to 15thNight
38%
840
25%
2319
14%
840
47%
840
28%
1479
March16th to endNight
38%
896
19%
2464
11%
896
45%
896
27%
1633
April1st to 15thNight
42%
838
22%
2275
12%
838
50%
838
32%
1409
April16th to endNight
49%
665
23%
1911
13%
665
56%
665
30%
1203
May1st to 15thNight
52%
630
17%
1890
11%
630
55%
630
24%
1272
May16th to endNight
61%
658
16%
1972
13%
657
63%
657
25%
1300
June1st to 15thNight
66%
630
14%
1890
11%
630
67%
630
25%
1273
June16th to endNight
72%
609
14%
1828
13%
609
72%
609
29%
1173
July1st to 15thNight
70%
555
10%
1665
9%
555
70%
555
24%
1139
July16th to endNight
72%
612
12%
1739
10%
579
74%
579
25%
1172
August1st to 15thNight
67%
575
13%
1715
12%
572
67%
572
22%
1205
August16th to endNight
68%
679
17%
1958
15%
679
69%
679
25%
1352
September1st to 15thNight
64%
780
16%
2145
14%
780
65%
780
25%
1489
September16th to endNight
56%
777
19%
2145
17%
777
58%
777
24%
1490
October1st to 15thNight
56%
780
28%
2257
24%
780
61%
780
31%
1399
October16th to endNight
54%
832
33%
2496
27%
832
66%
832
38%
1383
November1st to 15thNight
52%
820
27%
2558
22%
820
60%
820
32%
1497
November16th to endNight
50%
840
27%
2730
22%
840
60%
840
31%
1522
December1st to 15thNight
41%
840
24%
2730
16%
840
52%
840
24%
1705
December16th to endNight
38%
896
21%
2912
15%
896
47%
896
21%
1911

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
13%5%245%35%5%6%8%41%
54799
Night
13%5%2442445%7%44%
54216
TransparencyDay
39%7%12%20%15%4
54500
Night
38%6%11%20%18%4
54019
SeeingDay
18%7%18%24%18%12%
7856
Night
16%5%19%31%22%4
18048

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
15%6%24323435%48%
1881
16th to endDay
14%313323346%51%
2016
February1st to 15thDay
14%5%2442445%7%45%
1935
16th to endDay
16%5%2432345%6%43%
1840
March1st to 15thDay
16%424324347%46%
2299
16th to endDay
16%5%244345%5%6%42%
2463
April1st to 15thDay
12%31342446%9%47%
2333
16th to endDay
14%42443445%7%43%
2665
May1st to 15thDay
12%5%246%25%5%6%8%39%
2721
16th to endDay
12%5%25%5%35%5%7%8%38%
2847
June1st to 15thDay
9%5%25%6%37%6%7%9%34%
2730
16th to endDay
6%425%6%47%7%8%10%37%
2639
July1st to 15thDay
10%5%25%7%47%6%8%11%30%
2535
16th to endDay
9%435%7%47%8%8%11%29%
2673
August1st to 15thDay
13%6%25%7%47%8%7%9%26%
2487
16th to endDay
10%5%26%7%45%7%7%9%31%
2579
September1st to 15thDay
13%5%25%6%35%46%8%37%
2145
16th to endDay
17%5%25%435%46%7%36%
2145
October1st to 15thDay
15%5%13312345%53%
2031
16th to endDay
13%31341232459%
2080
November1st to 15thDay
12%5%23413346%52%
1959
16th to endDay
15%31332325%5%53%
1890
December1st to 15thDay
16%6%24423446%44%
1890
16th to endDay
20%7%24323446%40%
2016
January1st to 15thNight
16%5%13423436%48%
2717
16th to endNight
15%5%23313445%49%
2912
February1st to 15thNight
14%5%23323346%49%
2577
16th to endNight
15%5%2442445%6%43%
2205
March1st to 15thNight
14%5%25%42445%6%45%
2319
16th to endNight
15%5%2442336%6%42%
2464
April1st to 15thNight
12%5%1432445%6%49%
2275
16th to endNight
14%324424446%48%
1911
May1st to 15thNight
13%5%346%35%45%6%40%
1889
16th to endNight
13%4245%25%5%6%8%40%
1970
June1st to 15thNight
8%5%25%6%45%7%7%10%35%
1890
16th to endNight
6%4146%46%6%7%10%41%
1828
July1st to 15thNight
7%5%25%7%36%7%8%10%35%
1755
16th to endNight
5%5%26%6%37%7%8%12%34%
1847
August1st to 15thNight
13%5%36%5%25%7%7%9%34%
1726
16th to endNight
9%6%26%5%45%6%7%10%35%
1958
September1st to 15thNight
11%6%16%5%45%6%6%7%38%
2145
16th to endNight
18%6%25%5%24446%38%
2145
October1st to 15thNight
14%414424345%49%
2257
16th to endNight
12%41321334458%
2496
November1st to 15thNight
14%424323335%53%
2558
16th to endNight
14%313323346%52%
2730
December1st to 15thNight
16%5%2432435%5%44%
2730
16th to endNight
21%7%24423445%40%
2912

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%5%9%20%21%4
1882
16th to endDay
34%38%24%21%7%
2016
February1st to 15thDay
38%5%10%20%19%5%
1937
16th to endDay
41%410%22%16%4
1840
March1st to 15thDay
39%47%21%20%6%
2299
16th to endDay
40%7%12%19%17%2
2464
April1st to 15thDay
33%5%12%25%18%4
2333
16th to endDay
39%6%10%19%17%6%
2665
May1st to 15thDay
40%9%14%20%13%2
2721
16th to endDay
40%8%15%22%11%2
2851
June1st to 15thDay
41%10%17%20%8%
2730
16th to endDay
36%11%18%18%13%1
2639
July1st to 15thDay
42%11%17%16%9%2
2396
16th to endDay
41%12%18%16%8%1
2518
August1st to 15thDay
48%10%16%14%7%1
2474
16th to endDay
44%10%16%19%7%1
2579
September1st to 15thDay
43%7%13%20%11%3
2145
16th to endDay
45%7%11%15%18%2
2145
October1st to 15thDay
34%310%23%22%5%
2031
16th to endDay
30%36%25%25%9%
2080
November1st to 15thDay
33%39%18%27%7%
1959
16th to endDay
33%28%23%24%6%
1890
December1st to 15thDay
41%49%21%17%5%
1890
16th to endDay
44%5%9%19%15%4
2016
January1st to 15thNight
37%410%16%24%6%
2717
16th to endNight
36%48%21%23%6%
2912
February1st to 15thNight
36%49%22%21%4
2586
16th to endNight
40%411%20%18%3
2205
March1st to 15thNight
38%5%8%19%20%7%
2319
16th to endNight
41%5%10%21%17%3
2464
April1st to 15thNight
34%5%10%25%20%3
2275
16th to endNight
36%5%11%18%20%7%
1911
May1st to 15thNight
43%6%11%22%14%1
1890
16th to endNight
39%8%13%24%11%2
1972
June1st to 15thNight
39%10%18%22%8%1
1890
16th to endNight
34%10%19%19%12%2
1828
July1st to 15thNight
39%12%19%17%8%3
1665
16th to endNight
35%14%21%18%7%1
1739
August1st to 15thNight
42%11%18%14%10%
1715
16th to endNight
40%11%17%20%8%
1958
September1st to 15thNight
42%9%15%16%12%3
2145
16th to endNight
45%6%11%14%18%2
2145
October1st to 15thNight
36%5%9%22%21%4
2257
16th to endNight
29%35%23%28%9%
2496
November1st to 15thNight
35%37%18%25%10%
2558
16th to endNight
33%38%21%25%7%
2730
December1st to 15thNight
41%49%20%18%6%
2730
16th to endNight
45%410%17%17%3
2912

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%17%32%21%3
180
16th to endDay
18%25%31%20%4
192
February1st to 15thDay
22%19%37%16%4
180
16th to endDay
35%20%26%14%21
159
March1st to 15thDay
20%17%26%29%5%
379
16th to endDay
19%13%29%25%9%1
416
April1st to 15thDay
17%11%26%27%13%2
390
16th to endDay
19%7%21%25%18%7%
379
May1st to 15thDay
15%9%22%26%16%10%
408
16th to endDay
17%311%27%23%16%
459
June1st to 15thDay
13%212%25%26%18%
435
16th to endDay
9%114%26%27%19%
407
July1st to 15thDay
10%19%21%27%30%
365
16th to endDay
9%17%24%26%29%
390
August1st to 15thDay
20%7%21%24%25%
358
16th to endDay
12%26%20%28%29%
396
September1st to 15thDay
17%210%16%26%25%
375
16th to endDay
21%211%24%27%12%
374
October1st to 15thDay
20%314%27%24%10%
375
16th to endDay
14%6%17%34%19%7%
400
November1st to 15thDay
26%7%24%22%12%5%
287
16th to endDay
12%13%26%27%16%2
180
December1st to 15thDay
30%9%30%22%7%
180
16th to endDay
31%9%35%20%2
192
January1st to 15thNight
20%12%28%30%8%
840
16th to endNight
17%10%31%34%5%
896
February1st to 15thNight
16%11%29%37%3
824
16th to endNight
18%11%34%31%3
735
March1st to 15thNight
18%8%29%36%6%
840
16th to endNight
19%7%28%32%11%
896
April1st to 15thNight
16%9%27%32%13%
838
16th to endNight
15%6%20%36%19%
665
May1st to 15thNight
16%319%34%24%1
630
16th to endNight
16%28%28%37%5%
659
June1st to 15thNight
11%19%30%38%8%
630
16th to endNight
9%7%28%42%11%
609
July1st to 15thNight
12%321%52%9%
555
16th to endNight
6%1422%48%16%
612
August1st to 15thNight
16%1325%43%10%
575
16th to endNight
12%5%21%48%11%
679
September1st to 15thNight
13%28%22%42%10%
780
16th to endNight
20%111%27%34%5%
777
October1st to 15thNight
17%316%27%26%7%
780
16th to endNight
14%421%36%20%3
832
November1st to 15thNight
18%419%35%18%3
820
16th to endNight
16%9%20%34%18%1
840
December1st to 15thNight
21%7%23%36%10%
840
16th to endNight
25%7%23%36%7%
896
Page generated at 2019-06-24 20:41:32. Version ac04

Copyright 2019 A. Danko


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