Earwig Haven Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Earwig Haven Observatory clear sky chart from 2005-11-06 to 2024-01-14.

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%
22577
14%
74760
8%
22536
36%
22536
16%
53295

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
14%
760
8%
2649
2%
757
21%
757
7%
2130
January11th to 20thNight
17%
735
9%
2569
4%
735
23%
735
8%
2037
January21st to endNight
22%
792
14%
2696
8%
792
30%
792
12%
1963
February1st to 10thNight
15%
720
10%
2340
3%
720
24%
720
9%
1821
February11th to 20thNight
16%
701
13%
2272
4%
700
27%
700
13%
1664
February21st to endNight
21%
592
15%
1776
7%
592
32%
592
14%
1322
March1st to 10thNight
19%
720
15%
2156
7%
720
28%
720
14%
1617
March11th to 20thNight
21%
720
17%
1979
6%
720
31%
720
17%
1420
March21st to endNight
27%
792
21%
2065
8%
792
36%
792
21%
1461
April1st to 10thNight
22%
720
15%
1800
5%
720
28%
720
19%
1331
April11th to 20thNight
25%
711
17%
1775
6%
711
31%
711
20%
1286
April21st to endNight
27%
612
16%
1692
7%
612
33%
612
18%
1226
May1st to 10thNight
34%
360
17%
1440
13%
360
44%
360
17%
937
May11th to 20thNight
31%
354
21%
1416
15%
354
47%
354
18%
870
May21st to endNight
34%
389
14%
1551
10%
388
48%
388
23%
906
June1st to 10thNight
37%
360
10%
1440
10%
360
47%
360
17%
965
June11th to 20thNight
39%
360
13%
1440
15%
360
47%
360
21%
863
June21st to endNight
37%
360
11%
1440
14%
360
44%
360
17%
945
July1st to 10thNight
50%
350
15%
1400
19%
350
57%
350
25%
803
July11th to 20thNight
51%
348
16%
1392
22%
348
57%
348
25%
810
July21st to endNight
50%
394
15%
1486
16%
372
55%
372
23%
855
August1st to 10thNight
49%
397
16%
1461
14%
395
56%
395
23%
893
August11th to 20thNight
55%
538
18%
1602
12%
538
60%
538
30%
1018
August21st to endNight
45%
792
18%
1980
7%
792
49%
792
32%
1304
September1st to 10thNight
44%
720
17%
1800
8%
720
48%
720
32%
1220
September11th to 20thNight
50%
720
23%
1800
13%
720
55%
720
34%
1169
September21st to endNight
41%
720
21%
2037
15%
720
47%
720
26%
1349
October1st to 10thNight
35%
720
17%
2160
11%
720
43%
720
20%
1490
October11th to 20thNight
25%
720
15%
2160
7%
720
34%
720
16%
1567
October21st to endNight
24%
792
13%
2515
7%
792
33%
792
13%
1885
November1st to 10thNight
26%
740
16%
2407
9%
740
35%
740
17%
1672
November11th to 20thNight
21%
760
16%
2653
10%
760
32%
760
13%
1897
November21st to endNight
19%
760
10%
2660
4%
760
26%
760
10%
2022
December1st to 10thNight
16%
760
8%
2660
3%
760
21%
760
7%
2181
December11th to 20thNight
17%
760
12%
3243
6%
759
26%
759
8%
2453
December21st to endNight
13%
828
6%
4848
2%
817
19%
817
4%
3943

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
17%9%36%6%35%5%5%6%34%
74744
Night
18%10%47%6%3445%6%33%
75013
TransparencyDay
50%6%11%20%11%1
74449
Night
52%6%10%20%11%1
74842
SeeingDay
22%15%30%21%9%3
13362
Night
22%13%30%25%9%1
22587

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
15%16%6%10%8%345%5%5%22%
1517
11th to 20thDay
18%14%5%10%8%35%5%35%25%
1464
21st to endDay
13%14%5%8%6%5%6%5%5%5%26%
1659
February1st to 10thDay
15%14%5%9%8%46%5%6%5%23%
1620
11th to 20thDay
14%13%5%8%6%46%446%30%
1574
21st to endDay
19%13%39%6%35%6%5%6%25%
1480
March1st to 10thDay
15%10%5%7%8%45%5%5%5%30%
1800
11th to 20thDay
16%10%46%7%36%45%6%32%
1980
21st to endDay
19%10%35%43445%5%38%
2290
April1st to 10thDay
21%10%46%5%3445%6%33%
2160
11th to 20thDay
21%8%36%5%3445%5%38%
2134
21st to endDay
22%10%36%6%35%446%32%
2282
May1st to 10thDay
20%7%36%7%35%45%6%35%
2520
11th to 20thDay
15%7%36%5%345%5%7%40%
2478
21st to endDay
16%6%26%6%46%5%5%7%38%
2725
June1st to 10thDay
21%6%46%6%46%5%6%6%31%
2520
11th to 20thDay
14%5%25%5%36%5%6%8%39%
2520
21st to endDay
17%7%37%6%46%6%6%7%33%
2520
July1st to 10thDay
12%5%25%5%35%6%6%8%42%
2520
11th to 20thDay
12%5%35%5%35%6%7%9%40%
2520
21st to endDay
12%5%35%5%45%5%7%10%40%
2744
August1st to 10thDay
11%5%26%6%45%6%6%8%41%
2464
11th to 20thDay
12%5%26%6%46%5%6%8%40%
2281
21st to endDay
13%6%25%5%45%5%6%9%40%
2376
September1st to 10thDay
13%5%26%6%35%5%5%8%43%
2160
11th to 20thDay
13%435%435%5%6%8%45%
2160
21st to endDay
17%5%25%6%45%5%6%7%39%
1922
October1st to 10thDay
20%7%35%6%245%5%7%36%
1800
11th to 20thDay
23%7%36%6%45%5%5%6%29%
1800
21st to endDay
26%8%46%5%35%5%45%28%
1840
November1st to 10thDay
15%8%46%6%45%5%6%7%34%
1671
11th to 20thDay
19%11%37%7%46%45%5%29%
1525
21st to endDay
21%12%48%8%5%6%5%5%7%20%
1520
December1st to 10thDay
21%17%5%9%7%45%5%5%6%18%
1520
11th to 20thDay
22%13%48%7%35%5%45%25%
1906
21st to endDay
28%16%6%11%5%3433320%
2772
January1st to 10thNight
17%16%6%11%8%35%5%45%19%
2649
11th to 20thNight
18%15%6%10%7%45%43423%
2569
21st to endNight
12%14%6%8%7%4445%6%30%
2696
February1st to 10thNight
15%14%5%11%7%5%6%5%5%6%22%
2340
11th to 20thNight
14%11%5%10%8%35%45%5%30%
2270
21st to endNight
16%12%48%7%35%45%6%29%
1776
March1st to 10thNight
16%13%5%8%7%35%445%30%
2146
11th to 20thNight
16%12%5%7%6%33435%35%
1979
21st to endNight
18%8%35%5%3445%5%40%
2065
April1st to 10thNight
20%9%47%5%34446%34%
1800
11th to 20thNight
19%8%37%6%3435%6%37%
1775
21st to endNight
22%8%36%6%3445%6%33%
1692
May1st to 10thNight
22%6%25%5%35%5%7%6%35%
1440
11th to 20thNight
17%7%45%4345%5%6%41%
1415
21st to endNight
12%5%36%5%345%6%8%44%
1550
June1st to 10thNight
16%6%26%6%46%5%6%9%33%
1440
11th to 20thNight
15%5%36%5%25%46%8%43%
1440
21st to endNight
18%6%35%5%35%45%9%37%
1440
July1st to 10thNight
11%5%25%5%45%45%9%45%
1440
11th to 20thNight
11%6%25%445%5%6%9%43%
1440
21st to endNight
9%5%35%6%36%5%6%7%45%
1574
August1st to 10thNight
8%6%37%5%35%6%6%9%43%
1471
11th to 20thNight
10%5%16%445%5%6%8%46%
1602
21st to endNight
12%5%36%5%345%6%7%46%
1980
September1st to 10thNight
12%5%25%5%35%5%5%6%47%
1800
11th to 20thNight
14%42443445%7%49%
1800
21st to endNight
16%6%25%6%3445%6%44%
2037
October1st to 10thNight
17%8%35%5%35%5%5%6%38%
2160
11th to 20thNight
22%8%46%6%35%45%6%31%
2160
21st to endNight
23%9%46%5%4445%5%29%
2515
November1st to 10thNight
19%10%45%6%25%446%35%
2407
11th to 20thNight
18%10%47%6%45%5%5%6%31%
2653
21st to endNight
21%12%5%8%6%35%5%6%6%24%
2660
December1st to 10thNight
21%16%5%8%7%35%6%5%6%17%
2660
11th to 20thNight
22%14%5%7%6%44345%27%
3288
21st to endNight
31%16%49%5%3433418%
4884

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
66%7%8%14%6%
1518
11th to 20thDay
64%5%8%12%10%1
1464
21st to endDay
60%6%13%12%8%1
1659
February1st to 10thDay
62%5%10%17%42
1620
11th to 20thDay
57%412%17%9%1
1583
21st to endDay
60%5%9%14%10%1
1480
March1st to 10thDay
56%6%10%17%10%1
1803
11th to 20thDay
54%412%16%12%3
1980
21st to endDay
49%6%8%19%14%5%
2290
April1st to 10thDay
53%47%19%13%3
2160
11th to 20thDay
50%47%22%16%2
2134
21st to endDay
55%5%8%14%14%4
2282
May1st to 10thDay
50%5%8%19%15%4
2520
11th to 20thDay
45%6%7%22%17%3
2482
21st to endDay
44%7%12%21%13%2
2725
June1st to 10thDay
53%6%10%18%12%1
2520
11th to 20thDay
42%8%11%24%13%3
2520
21st to endDay
49%9%11%19%11%1
2520
July1st to 10thDay
37%7%13%27%15%1
2450
11th to 20thDay
38%8%15%27%11%
2445
21st to endDay
40%10%13%27%11%
2591
August1st to 10thDay
40%9%15%25%10%
2450
11th to 20thDay
40%8%15%26%10%1
2281
21st to endDay
40%7%13%27%12%1
2376
September1st to 10thDay
39%8%13%28%12%
2160
11th to 20thDay
36%8%12%31%13%1
2160
21st to endDay
43%7%14%27%9%
1922
October1st to 10thDay
49%7%11%23%10%1
1800
11th to 20thDay
56%7%14%16%7%1
1800
21st to endDay
59%5%12%15%8%1
1840
November1st to 10thDay
48%8%14%22%7%1
1671
11th to 20thDay
57%6%12%15%9%1
1525
21st to endDay
64%6%12%10%7%
1520
December1st to 10thDay
68%7%11%10%31
1520
11th to 20thDay
62%7%13%13%5%
1906
21st to endDay
72%46%14%3
2772
January1st to 10thNight
67%6%10%12%6%
2649
11th to 20thNight
66%5%9%11%8%1
2569
21st to endNight
56%6%8%18%11%1
2696
February1st to 10thNight
63%5%10%15%7%1
2340
11th to 20thNight
57%411%19%8%1
2272
21st to endNight
57%5%9%18%11%1
1776
March1st to 10thNight
57%5%9%16%11%2
2156
11th to 20thNight
53%311%19%12%2
1980
21st to endNight
48%5%8%19%16%4
2065
April1st to 10thNight
52%48%18%15%2
1800
11th to 20thNight
50%47%21%16%1
1775
21st to endNight
52%5%8%16%16%4
1692
May1st to 10thNight
48%5%7%19%15%5%
1440
11th to 20thNight
44%5%7%23%18%3
1416
21st to endNight
38%6%15%20%18%3
1551
June1st to 10thNight
47%8%11%23%10%1
1440
11th to 20thNight
40%6%11%23%18%2
1440
21st to endNight
45%8%12%20%13%1
1440
July1st to 10thNight
35%8%11%27%17%2
1400
11th to 20thNight
37%7%13%31%13%
1392
21st to endNight
36%7%15%27%14%
1486
August1st to 10thNight
37%9%16%23%14%1
1461
11th to 20thNight
36%8%15%28%12%
1602
21st to endNight
36%8%15%29%12%
1980
September1st to 10thNight
38%7%10%29%14%1
1800
11th to 20thNight
34%7%13%35%10%1
1800
21st to endNight
42%6%11%30%11%
2037
October1st to 10thNight
47%6%10%22%14%1
2160
11th to 20thNight
53%6%12%20%9%
2160
21st to endNight
57%6%12%16%8%
2515
November1st to 10thNight
51%5%14%21%9%1
2407
11th to 20thNight
54%6%12%18%9%1
2653
21st to endNight
60%6%13%15%5%
2660
December1st to 10thNight
68%7%9%12%4
2660
11th to 20thNight
61%5%9%16%7%1
3288
21st to endNight
73%47%13%4
4884

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
23%21%30%22%4
180
11th to 20thDay
28%20%32%16%31
166
21st to endDay
21%20%35%18%5%
210
February1st to 10thDay
33%23%33%10%
240
11th to 20thDay
26%28%39%7%1
241
21st to endDay
29%21%33%14%3
346
March1st to 10thDay
26%18%34%17%5%
420
11th to 20thDay
26%18%35%17%41
420
21st to endDay
30%20%26%16%8%1
462
April1st to 10thDay
28%20%30%15%6%1
420
11th to 20thDay
31%20%21%17%10%2
412
21st to endDay
32%18%27%15%5%2
420
May1st to 10thDay
25%13%32%20%7%2
423
11th to 20thDay
17%18%34%21%6%3
447
21st to endDay
17%15%33%23%11%1
485
June1st to 10thDay
24%12%32%22%8%2
450
11th to 20thDay
16%16%29%25%12%3
450
21st to endDay
17%15%30%24%10%4
450
July1st to 10thDay
11%8%29%33%15%4
445
11th to 20thDay
13%8%30%30%14%4
444
21st to endDay
14%8%30%30%15%3
488
August1st to 10thDay
15%7%29%28%18%4
446
11th to 20thDay
12%8%23%31%17%9%
439
21st to endDay
14%11%28%24%13%8%
495
September1st to 10thDay
16%12%28%20%15%8%
450
11th to 20thDay
13%8%28%24%18%10%
450
21st to endDay
17%10%32%20%16%5%
450
October1st to 10thDay
27%12%25%20%12%6%
450
11th to 20thDay
25%19%27%21%6%2
450
21st to endDay
30%19%24%23%4
425
November1st to 10thDay
25%16%32%17%8%1
365
11th to 20thDay
28%19%34%11%5%2
185
21st to endDay
29%17%34%14%41
180
December1st to 10thDay
32%14%36%16%21
180
11th to 20thDay
29%26%31%11%21
180
21st to endDay
34%19%31%13%21
198
January1st to 10thNight
26%16%35%20%4
760
11th to 20thNight
27%17%30%20%5%
735
21st to endNight
19%13%35%27%5%1
792
February1st to 10thNight
23%17%35%20%4
720
11th to 20thNight
22%18%38%18%4
703
21st to endNight
26%18%30%22%4
592
March1st to 10thNight
24%16%33%23%4
720
11th to 20thNight
23%19%32%20%6%
720
21st to endNight
24%15%28%25%8%
792
April1st to 10thNight
26%16%29%23%5%
720
11th to 20thNight
24%18%26%23%8%
711
21st to endNight
26%14%27%24%7%1
612
May1st to 10thNight
23%9%29%28%9%1
360
11th to 20thNight
21%13%28%27%10%
354
21st to endNight
13%7%41%25%14%
389
June1st to 10thNight
18%6%32%34%8%1
360
11th to 20thNight
17%8%28%34%13%1
360
21st to endNight
20%6%31%30%13%1
360
July1st to 10thNight
9%7%26%43%14%1
350
11th to 20thNight
13%6%24%41%15%1
348
21st to endNight
10%430%41%14%2
394
August1st to 10thNight
9%426%39%21%
397
11th to 20thNight
12%222%38%24%3
538
21st to endNight
13%6%27%32%20%2
792
September1st to 10thNight
14%6%31%30%18%1
720
11th to 20thNight
16%7%22%31%20%3
720
21st to endNight
18%10%26%26%19%2
720
October1st to 10thNight
20%11%27%25%15%1
720
11th to 20thNight
26%13%29%23%8%1
720
21st to endNight
27%15%28%25%6%
792
November1st to 10thNight
27%13%28%22%9%1
740
11th to 20thNight
23%17%33%17%9%1
760
21st to endNight
29%16%26%21%7%
760
December1st to 10thNight
30%16%30%19%4
760
11th to 20thNight
28%16%30%20%5%1
760
21st to endNight
34%14%30%18%4
836
Page generated at 2024-01-11 04:22:42. Version ac07

Copyright 2024 Attilla Danko


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