This page made possible by the sponsorship of: David T. and Jean M. Long.

Warbler's Hideaway Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Warbler's Hideaway Observatory clear sky chart from 2005-11-05 to 2017-09-10.

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
30%
15632
12%
46773
7%
15590
34%
15590
17%
34360

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
13%
900
5%
2506
2%
895
16%
895
7%
2180
January16th to endNight
15%
960
7%
2688
2%
960
19%
960
9%
2275
February1st to 15thNight
12%
710
7%
2272
3%
710
17%
710
8%
1861
February16th to endNight
20%
631
10%
1893
4%
631
25%
631
10%
1538
March1st to 15thNight
23%
720
14%
2109
7%
720
29%
720
17%
1533
March16th to endNight
30%
766
18%
2110
10%
766
36%
766
22%
1457
April1st to 15thNight
25%
539
14%
1767
8%
539
32%
539
16%
1261
April16th to endNight
32%
540
17%
1620
7%
540
40%
540
23%
1094
May1st to 15thNight
33%
540
13%
1620
7%
540
40%
540
20%
1126
May16th to endNight
40%
544
15%
1530
7%
543
49%
543
28%
992
June1st to 15thNight
40%
360
13%
1260
10%
360
47%
360
23%
783
June16th to endNight
48%
360
13%
1260
11%
360
53%
360
25%
774
July1st to 15thNight
58%
498
14%
1348
10%
498
61%
498
38%
800
July16th to endNight
55%
564
15%
1417
10%
531
56%
531
34%
893
August1st to 15thNight
58%
539
18%
1596
14%
536
63%
536
35%
931
August16th to endNight
56%
573
19%
1746
15%
573
59%
573
31%
1047
September1st to 15thNight
48%
611
18%
1836
13%
611
53%
611
29%
1141
September16th to endNight
47%
657
17%
1815
12%
657
50%
657
28%
1205
October1st to 15thNight
35%
660
17%
1886
11%
660
41%
660
22%
1326
October16th to endNight
22%
704
10%
2262
6%
704
28%
704
13%
1713
November1st to 15thNight
26%
700
14%
2276
11%
700
32%
700
14%
1655
November16th to endNight
17%
720
8%
2448
5%
720
22%
720
9%
1964
December1st to 15thNight
12%
876
3%
2676
1%
876
14%
876
6%
2325
December16th to endNight
12%
960
5%
2832
1%
960
15%
960
6%
2486

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%47%6%3445%7%30%
47849
Night
14%10%47%6%3445%6%31%
46941
Cloud CoverDay
14%10%47%6%3445%7%30%
47858
Night
14%10%47%6%34446%31%
46946
TransparencyDay
53%7%11%17%9%
47535
Night
53%6%12%17%8%
46773
SeeingDay
18%12%31%22%10%4
5932
Night
19%12%32%26%9%1
15636

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
16%17%7%12%9%35%435%13%
1432
16th to endDay
12%16%9%14%11%5%6%33412%
1536
February1st to 15thDay
11%16%8%11%12%46%5%3415%
1587
16th to endDay
12%18%7%11%10%44445%17%
1580
March1st to 15thDay
14%10%49%7%35%5%5%5%27%
1841
16th to endDay
15%12%47%6%3445%5%30%
2124
April1st to 15thDay
20%14%45%413446%30%
2181
16th to endDay
16%10%35%424447%36%
2340
May1st to 15thDay
18%7%35%5%3445%7%33%
2331
16th to endDay
13%5%26%5%3445%7%40%
2579
June1st to 15thDay
14%7%245%35%46%8%36%
2700
16th to endDay
13%6%25%5%445%6%8%36%
2700
July1st to 15thDay
9%5%26%5%35%6%5%9%40%
2529
16th to endDay
10%5%245%35%5%6%9%38%
2655
August1st to 15thDay
9%5%25%6%45%5%7%9%38%
2353
16th to endDay
14%7%25%5%25%5%5%7%38%
2453
September1st to 15thDay
15%5%35%5%3445%8%38%
1999
16th to endDay
15%6%35%435%45%8%37%
1815
October1st to 15thDay
21%10%46%5%23346%32%
1744
16th to endDay
23%16%47%6%35%5%46%16%
1609
November1st to 15thDay
15%13%47%5%3445%6%27%
1582
16th to endDay
18%19%7%11%7%23335%16%
1509
December1st to 15thDay
16%18%7%13%9%44345%12%
1281
16th to endDay
20%19%11%12%8%333349%
1389
January1st to 15thNight
17%14%7%11%9%5%6%43414%
2506
16th to endNight
12%14%7%11%9%5%5%5%46%16%
2688
February1st to 15thNight
11%16%6%10%9%46%44419%
2270
16th to endNight
13%15%6%11%8%35%44421%
1893
March1st to 15thNight
12%11%5%6%5%35%5%45%33%
2096
16th to endNight
14%8%36%42345%6%38%
2110
April1st to 15thNight
20%11%35%5%235%5%5%31%
1767
16th to endNight
16%8%25%43335%6%39%
1620
May1st to 15thNight
13%6%35%6%46%5%6%7%34%
1620
16th to endNight
11%6%245%3446%8%40%
1528
June1st to 15thNight
11%5%25%5%346%6%6%41%
1260
16th to endNight
9%325%5%36%47%7%43%
1260
July1st to 15thNight
6%424425%46%8%50%
1428
16th to endNight
6%424425%46%7%50%
1513
August1st to 15thNight
6%315%5%3445%7%51%
1605
16th to endNight
10%5%25%423348%49%
1746
September1st to 15thNight
13%5%25%423436%47%
1836
16th to endNight
15%6%25%43435%8%42%
1815
October1st to 15thNight
18%8%36%5%33336%37%
1886
16th to endNight
21%11%36%5%3445%6%27%
2262
November1st to 15thNight
13%12%5%6%6%345%5%7%28%
2276
16th to endNight
17%17%5%8%6%34345%20%
2448
December1st to 15thNight
17%16%6%10%9%5%6%5%5%413%
2676
16th to endNight
18%19%8%12%7%35%43412%
2832

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
17%16%7%12%8%44445%14%
1432
16th to endDay
12%16%10%13%11%5%6%43412%
1536
February1st to 15thDay
12%16%8%11%12%45%5%3416%
1587
16th to endDay
12%18%7%10%10%34445%17%
1580
March1st to 15thDay
14%11%49%7%345%5%6%27%
1851
16th to endDay
15%12%47%6%3445%5%30%
2123
April1st to 15thDay
19%14%35%413436%31%
2181
16th to endDay
16%11%35%42445%6%36%
2340
May1st to 15thDay
18%7%35%5%25%45%7%33%
2331
16th to endDay
12%6%26%5%35%45%6%40%
2579
June1st to 15thDay
14%6%35%5%345%6%8%35%
2700
16th to endDay
13%6%35%6%345%6%8%36%
2700
July1st to 15thDay
9%5%35%5%45%5%6%9%39%
2529
16th to endDay
10%6%245%36%5%6%9%38%
2655
August1st to 15thDay
9%5%26%6%35%5%6%9%37%
2353
16th to endDay
15%6%35%5%25%46%6%39%
2453
September1st to 15thDay
15%6%245%3445%8%38%
1999
16th to endDay
14%7%35%43445%8%37%
1815
October1st to 15thDay
20%11%36%424346%32%
1744
16th to endDay
22%17%47%6%345%46%16%
1609
November1st to 15thDay
15%14%5%6%5%3446%6%27%
1582
16th to endDay
18%19%8%11%7%2333416%
1509
December1st to 15thDay
16%18%8%13%9%33345%13%
1281
16th to endDay
21%18%11%12%8%233249%
1389
January1st to 15thNight
17%14%7%12%9%45%5%3415%
2506
16th to endNight
12%14%7%12%9%5%5%45%6%16%
2688
February1st to 15thNight
11%15%7%11%9%46%5%45%19%
2263
16th to endNight
13%15%5%11%8%35%5%4421%
1893
March1st to 15thNight
13%11%5%6%6%35%45%5%33%
2109
16th to endNight
15%8%36%423446%39%
2110
April1st to 15thNight
20%11%26%4235%5%5%31%
1767
16th to endNight
16%8%25%5%3335%6%39%
1620
May1st to 15thNight
13%6%446%46%5%5%8%34%
1619
16th to endNight
11%6%345%245%5%9%41%
1528
June1st to 15thNight
12%5%25%5%345%5%7%42%
1260
16th to endNight
8%425%5%36%46%9%43%
1260
July1st to 15thNight
6%4145%2445%8%51%
1428
16th to endNight
5%4244245%6%8%48%
1513
August1st to 15thNight
6%425%5%3445%7%51%
1605
16th to endNight
10%5%24423347%50%
1746
September1st to 15thNight
13%5%24424436%47%
1836
16th to endNight
14%6%25%43435%7%42%
1815
October1st to 15thNight
18%7%36%5%34336%38%
1886
16th to endNight
22%11%35%5%2445%6%27%
2262
November1st to 15thNight
13%12%5%7%5%345%5%7%28%
2276
16th to endNight
17%17%5%9%6%34445%21%
2448
December1st to 15thNight
18%15%7%10%10%45%45%413%
2676
16th to endNight
18%18%9%13%6%25%43412%
2832

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
73%7%8%8%2
1433
16th to endDay
76%6%6%7%2
1536
February1st to 15thDay
71%6%9%8%3
1589
16th to endDay
67%6%9%11%4
1580
March1st to 15thDay
56%6%12%17%6%
1851
16th to endDay
54%5%11%19%7%1
2124
April1st to 15thDay
54%411%18%10%
2181
16th to endDay
47%6%13%14%15%2
2340
May1st to 15thDay
49%7%9%19%10%2
2331
16th to endDay
42%7%12%23%13%1
2583
June1st to 15thDay
43%8%12%23%11%
2700
16th to endDay
43%8%15%20%11%1
2700
July1st to 15thDay
39%8%11%25%15%1
2380
16th to endDay
39%8%14%21%13%1
2488
August1st to 15thDay
40%9%13%23%12%
2338
16th to endDay
42%7%13%21%12%1
2453
September1st to 15thDay
42%7%12%22%12%1
1999
16th to endDay
44%6%17%22%9%
1815
October1st to 15thDay
53%6%9%22%8%
1744
16th to endDay
67%7%12%9%3
1609
November1st to 15thDay
56%6%12%17%7%
1582
16th to endDay
72%5%10%8%3
1509
December1st to 15thDay
75%5%8%8%1
1281
16th to endDay
80%46%5%1
1389
January1st to 15thNight
74%5%8%8%3
2506
16th to endNight
68%7%11%9%2
2688
February1st to 15thNight
67%6%9%12%3
2272
16th to endNight
65%6%11%11%4
1893
March1st to 15thNight
52%5%11%19%10%
2109
16th to endNight
45%5%13%21%12%1
2110
April1st to 15thNight
52%5%9%19%11%1
1767
16th to endNight
45%412%19%15%2
1620
May1st to 15thNight
46%7%12%19%10%3
1620
16th to endNight
39%6%13%24%13%2
1530
June1st to 15thNight
40%6%13%23%16%
1260
16th to endNight
36%9%14%25%13%1
1260
July1st to 15thNight
29%7%14%29%18%
1348
16th to endNight
32%8%16%27%14%
1417
August1st to 15thNight
30%6%18%29%14%
1596
16th to endNight
33%6%17%26%14%1
1746
September1st to 15thNight
37%5%13%29%13%1
1836
16th to endNight
40%6%16%27%8%
1815
October1st to 15thNight
48%5%10%23%10%
1886
16th to endNight
56%7%14%16%4
2262
November1st to 15thNight
53%7%14%15%8%
2276
16th to endNight
64%6%13%11%2
2448
December1st to 15thNight
72%8%9%7%1
2676
16th to endNight
75%5%9%6%2
2832

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
21%15%53%8%1
90
16th to endDay
36%9%33%15%5%
96
February1st to 15thDay
22%26%40%10%1
90
16th to endDay
19%28%39%9%2
81
March1st to 15thDay
27%19%34%12%4
141
16th to endDay
26%12%27%22%10%1
288
April1st to 15thDay
25%13%28%21%10%
270
16th to endDay
22%14%32%15%11%3
270
May1st to 15thDay
20%16%33%14%11%3
288
16th to endDay
17%14%34%22%9%2
464
June1st to 15thDay
17%16%30%25%8%1
495
16th to endDay
15%12%34%25%7%4
495
July1st to 15thDay
13%9%32%25%14%5%
475
16th to endDay
11%9%32%28%12%5%
515
August1st to 15thDay
10%326%30%16%13%
326
16th to endDay
21%5%21%24%19%7%
332
September1st to 15thDay
16%425%24%18%10%
294
16th to endDay
15%8%25%25%15%8%
254
October1st to 15thDay
26%10%30%21%9%1
255
16th to endDay
28%23%31%12%4
121
November1st to 15thDay
17%14%35%22%7%2
90
16th to endDay
19%26%38%11%21
71
December1st to 15thDay
30%31%30%331
60
16th to endDay
29%40%25%4
71
January1st to 15thNight
25%16%33%19%4
900
16th to endNight
17%15%40%21%5%
960
February1st to 15thNight
17%21%40%17%3
713
16th to endNight
23%17%30%24%4
631
March1st to 15thNight
18%18%35%21%6%
720
16th to endNight
18%11%34%27%7%
766
April1st to 15thNight
23%13%33%24%4
539
16th to endNight
19%11%34%26%7%1
540
May1st to 15thNight
14%10%37%27%8%
540
16th to endNight
14%8%32%30%12%
545
June1st to 15thNight
14%6%33%35%9%
360
16th to endNight
9%5%30%39%13%
360
July1st to 15thNight
8%424%43%18%1
498
16th to endNight
8%326%38%21%1
564
August1st to 15thNight
9%223%40%22%2
539
16th to endNight
13%419%39%20%1
573
September1st to 15thNight
14%6%26%28%19%5%
611
16th to endNight
18%5%23%31%15%5%
657
October1st to 15thNight
22%7%29%28%10%
660
16th to endNight
28%13%30%22%4
704
November1st to 15thNight
20%15%33%20%8%1
700
16th to endNight
25%15%35%20%2
720
December1st to 15thNight
25%18%37%16%2
876
16th to endNight
25%17%36%16%3
960
Page generated at 2017-09-11 19:35:17. Version ac04

Copyright 2017 A. Danko


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