Wild Apple Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Wild Apple Observatory clear sky chart from 2005-11-05 to 2017-10-06.

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
36%
16103
17%
47060
10%
16060
43%
16060
24%
31247

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
21%
900
14%
2506
5%
895
28%
895
18%
1828
January16th to endNight
20%
960
12%
2616
3%
960
28%
960
17%
1960
February1st to 15thNight
23%
871
14%
2283
3%
871
30%
871
20%
1632
February16th to endNight
25%
631
19%
1893
8%
631
35%
631
19%
1290
March1st to 15thNight
26%
699
15%
2139
7%
699
33%
699
19%
1432
March16th to endNight
30%
576
16%
2010
12%
576
38%
576
17%
1387
April1st to 15thNight
29%
539
16%
1797
10%
539
39%
539
19%
1212
April16th to endNight
33%
540
19%
1776
12%
540
44%
540
21%
1189
May1st to 15thNight
32%
540
16%
1491
8%
540
39%
540
22%
1065
May16th to endNight
48%
563
17%
1497
9%
561
54%
561
33%
955
June1st to 15thNight
49%
540
15%
1440
9%
540
52%
540
34%
912
June16th to endNight
51%
540
17%
1440
9%
540
55%
540
35%
905
July1st to 15thNight
66%
510
19%
1360
11%
510
69%
510
46%
772
July16th to endNight
66%
564
22%
1417
15%
531
69%
531
46%
808
August1st to 15thNight
68%
539
22%
1545
20%
536
72%
536
38%
893
August16th to endNight
64%
573
20%
1910
23%
573
66%
573
32%
1097
September1st to 15thNight
63%
540
27%
1800
27%
540
68%
540
38%
944
September16th to endNight
54%
672
26%
1935
18%
672
61%
672
37%
1124
October1st to 15thNight
42%
684
23%
2043
16%
684
48%
684
30%
1248
October16th to endNight
32%
704
17%
2200
10%
704
41%
704
22%
1440
November1st to 15thNight
34%
700
23%
2276
15%
700
44%
700
26%
1391
November16th to endNight
24%
858
16%
2478
8%
858
32%
858
20%
1719
December1st to 15thNight
20%
900
11%
2520
3%
900
26%
900
15%
1897
December16th to endNight
18%
960
11%
2688
3%
960
26%
960
12%
2147

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%8%36%5%3445%7%36%
48140
Night
13%7%35%5%3445%6%40%
47228
Cloud CoverDay
13%8%36%5%3445%7%36%
48148
Night
13%7%35%5%2445%6%40%
47233
TransparencyDay
46%5%13%22%11%1
47825
Night
43%412%23%13%1
47061
SeeingDay
15%7%27%26%16%5%
6111
Night
17%8%31%30%11%1
16106

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
10%11%6%9%5%36%5%47%28%
1432
16th to endDay
11%12%7%12%8%24446%22%
1605
February1st to 15thDay
13%13%6%6%5%23447%31%
1579
16th to endDay
13%11%37%7%25%346%33%
1580
March1st to 15thDay
14%10%46%5%23446%35%
1820
16th to endDay
18%10%46%6%33437%32%
2212
April1st to 15thDay
17%10%47%6%34446%29%
2151
16th to endDay
20%8%36%5%24345%34%
2184
May1st to 15thDay
17%8%37%7%35%45%7%28%
2457
16th to endDay
13%5%26%6%35%5%6%8%35%
2617
June1st to 15thDay
14%435%435%5%6%8%37%
2520
16th to endDay
9%5%25%6%45%5%7%9%38%
2520
July1st to 15thDay
5%425%5%346%7%9%44%
2520
16th to endDay
8%5%25%6%35%5%6%10%39%
2655
August1st to 15thDay
7%425%6%36%6%7%9%40%
2403
16th to endDay
12%5%25%5%25%45%7%42%
2292
September1st to 15thDay
13%42442436%7%47%
2160
16th to endDay
11%6%25%43345%8%44%
2013
October1st to 15thDay
14%7%35%423235%46%
1712
16th to endDay
16%9%36%5%2335%6%38%
1671
November1st to 15thDay
12%8%36%5%33445%42%
1582
16th to endDay
15%11%36%5%34236%37%
1479
December1st to 15thDay
18%13%47%5%34346%28%
1440
16th to endDay
19%15%6%9%6%25%5%45%20%
1536
January1st to 15thNight
14%11%48%6%3435%5%33%
2506
16th to endNight
12%11%5%10%7%35%446%27%
2616
February1st to 15thNight
10%12%5%7%5%35%45%5%35%
2280
16th to endNight
14%11%36%5%24445%36%
1893
March1st to 15thNight
16%9%35%5%2335%6%38%
2126
16th to endNight
17%9%35%6%3445%6%32%
2010
April1st to 15thNight
20%6%35%43445%5%35%
1797
16th to endNight
20%7%24423447%37%
1776
May1st to 15thNight
17%7%25%5%345%5%8%34%
1491
16th to endNight
9%425%4245%6%8%44%
1496
June1st to 15thNight
11%5%244345%5%9%43%
1440
16th to endNight
8%424425%5%6%8%47%
1440
July1st to 15thNight
6%21332446%10%55%
1440
16th to endNight
5%31432446%9%54%
1513
August1st to 15thNight
5%3145%35%46%8%50%
1554
16th to endNight
10%42442435%6%51%
1910
September1st to 15thNight
7%413423337%57%
1800
16th to endNight
6%423435%45%8%51%
1935
October1st to 15thNight
12%6%2442435%5%48%
2043
16th to endNight
16%7%35%42345%7%39%
2200
November1st to 15thNight
12%7%24424445%46%
2276
16th to endNight
18%8%37%433446%36%
2478
December1st to 15thNight
19%11%37%5%35%5%45%28%
2520
16th to endNight
21%13%5%8%5%34445%22%
2688

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
11%11%6%9%5%26%446%29%
1432
16th to endDay
12%12%6%12%8%34446%23%
1605
February1st to 15thDay
13%13%6%7%5%34436%31%
1579
16th to endDay
13%12%37%7%35%436%33%
1580
March1st to 15thDay
15%10%46%423446%35%
1830
16th to endDay
18%9%37%5%23437%32%
2210
April1st to 15thDay
17%10%47%6%34446%29%
2151
16th to endDay
20%9%26%5%24245%34%
2184
May1st to 15thDay
17%8%37%7%35%46%6%28%
2457
16th to endDay
13%6%26%5%345%6%8%36%
2617
June1st to 15thDay
14%5%25%5%35%5%5%8%38%
2520
16th to endDay
10%425%6%45%5%7%8%39%
2520
July1st to 15thDay
6%425%5%345%7%9%44%
2520
16th to endDay
8%5%35%6%35%5%6%9%40%
2655
August1st to 15thDay
7%425%6%46%5%7%9%40%
2403
16th to endDay
12%5%25%5%3445%7%42%
2292
September1st to 15thDay
13%41443435%6%47%
2160
16th to endDay
10%6%25%43435%7%44%
2013
October1st to 15thDay
15%6%25%5%24335%46%
1712
16th to endDay
17%9%36%5%24345%38%
1671
November1st to 15thDay
12%7%36%5%3345%5%42%
1582
16th to endDay
15%10%37%5%34236%37%
1479
December1st to 15thDay
18%13%5%8%5%24347%28%
1440
16th to endDay
20%14%6%8%5%35%5%4421%
1536
January1st to 15thNight
14%10%48%6%2435%5%33%
2506
16th to endNight
12%11%6%10%6%345%46%28%
2616
February1st to 15thNight
10%12%47%5%34445%35%
2273
16th to endNight
14%11%36%5%14446%36%
1893
March1st to 15thNight
16%8%45%5%23346%38%
2139
16th to endNight
17%9%35%6%3445%7%32%
2010
April1st to 15thNight
20%6%345%34446%35%
1797
16th to endNight
20%8%24424347%37%
1776
May1st to 15thNight
17%7%35%4335%5%8%34%
1490
16th to endNight
9%435%43446%9%44%
1496
June1st to 15thNight
11%5%25%335%46%8%43%
1440
16th to endNight
9%4244245%5%9%47%
1440
July1st to 15thNight
6%21332436%10%56%
1440
16th to endNight
5%31341445%10%54%
1513
August1st to 15thNight
5%315%5%345%5%8%50%
1554
16th to endNight
10%42333435%7%51%
1910
September1st to 15thNight
8%313423347%57%
1800
16th to endNight
6%4135%2445%7%51%
1935
October1st to 15thNight
12%6%24423446%48%
2043
16th to endNight
16%6%345%23447%40%
2200
November1st to 15thNight
12%7%24424445%46%
2276
16th to endNight
18%8%36%5%33445%37%
2478
December1st to 15thNight
19%11%37%5%25%5%45%28%
2520
16th to endNight
21%13%5%7%6%3444423%
2688

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
53%5%14%17%9%
1433
16th to endDay
60%412%14%6%
1605
February1st to 15thDay
54%411%21%7%
1580
16th to endDay
52%411%21%8%1
1580
March1st to 15thDay
49%5%13%21%9%1
1830
16th to endDay
52%412%22%6%
2212
April1st to 15thDay
54%410%19%9%
2151
16th to endDay
52%410%19%11%1
2184
May1st to 15thDay
53%5%12%20%7%
2457
16th to endDay
44%7%12%21%13%1
2621
June1st to 15thDay
41%6%14%23%13%
2520
16th to endDay
38%7%15%22%14%1
2520
July1st to 15thDay
33%7%16%25%15%1
2371
16th to endDay
38%6%16%23%12%2
2488
August1st to 15thDay
36%7%13%27%12%1
2388
16th to endDay
39%5%13%25%13%2
2292
September1st to 15thDay
35%410%29%18%
2160
16th to endDay
38%413%28%14%
2013
October1st to 15thDay
41%310%26%17%
1712
16th to endDay
47%413%24%10%
1671
November1st to 15thDay
43%412%25%12%1
1582
16th to endDay
50%418%21%5%
1479
December1st to 15thDay
57%414%17%6%
1440
16th to endDay
64%312%11%7%
1536
January1st to 15thNight
53%410%20%11%
2506
16th to endNight
56%414%16%8%
2616
February1st to 15thNight
49%412%21%11%1
2283
16th to endNight
48%412%23%8%2
1893
March1st to 15thNight
46%5%13%20%13%1
2139
16th to endNight
51%411%23%7%1
2010
April1st to 15thNight
48%49%22%13%1
1797
16th to endNight
47%5%9%21%13%3
1776
May1st to 15thNight
48%6%11%19%13%
1491
16th to endNight
35%6%15%24%16%1
1498
June1st to 15thNight
35%5%13%26%17%
1440
16th to endNight
33%6%13%22%20%2
1440
July1st to 15thNight
24%5%11%34%19%3
1360
16th to endNight
24%6%17%29%18%3
1417
August1st to 15thNight
29%5%13%30%19%2
1545
16th to endNight
33%5%12%28%16%3
1910
September1st to 15thNight
27%411%27%27%1
1800
16th to endNight
30%5%12%32%18%
1935
October1st to 15thNight
36%410%25%20%1
2043
16th to endNight
44%413%24%13%
2200
November1st to 15thNight
39%412%23%17%2
2276
16th to endNight
49%314%22%9%
2478
December1st to 15thNight
57%411%19%6%
2520
16th to endNight
64%410%13%5%1
2688

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%14%35%26%2
90
16th to endDay
25%11%31%21%10%
96
February1st to 15thDay
17%20%37%15%8%
90
16th to endDay
29%14%30%19%4
81
March1st to 15thDay
31%6%42%15%22
90
16th to endDay
28%10%27%20%10%2
196
April1st to 15thDay
21%11%34%22%9%
270
16th to endDay
22%11%26%23%12%2
270
May1st to 15thDay
18%12%34%23%9%2
414
16th to endDay
17%10%26%25%15%5%
517
June1st to 15thDay
15%6%26%28%19%4
495
16th to endDay
11%7%32%26%16%5%
495
July1st to 15thDay
8%324%30%20%12%
475
16th to endDay
9%227%29%21%9%
515
August1st to 15thDay
8%221%34%25%8%
481
16th to endDay
16%5%16%26%24%12%
332
September1st to 15thDay
12%418%29%25%9%
315
16th to endDay
8%6%25%31%22%5%
314
October1st to 15thDay
12%7%31%30%15%2
113
16th to endDay
21%9%39%25%4
96
November1st to 15thDay
5%13%27%31%18%3
90
16th to endDay
35%11%34%12%6%
90
December1st to 15thDay
22%13%40%18%5%
90
16th to endDay
35%21%32%7%3
96
January1st to 15thNight
20%12%38%21%7%
900
16th to endNight
18%10%41%26%3
960
February1st to 15thNight
17%11%38%26%6%
874
16th to endNight
20%13%34%24%6%
631
March1st to 15thNight
20%11%34%24%7%
699
16th to endNight
20%9%33%27%8%
576
April1st to 15thNight
22%10%33%26%5%
539
16th to endNight
22%7%32%28%7%
540
May1st to 15thNight
20%6%35%27%9%
540
16th to endNight
10%430%39%15%
563
June1st to 15thNight
14%424%42%14%
540
16th to endNight
10%329%39%16%
540
July1st to 15thNight
8%217%40%28%3
510
16th to endNight
6%119%43%26%2
564
August1st to 15thNight
7%115%46%26%2
539
16th to endNight
13%113%43%23%4
573
September1st to 15thNight
9%221%33%25%7%
540
16th to endNight
9%5%24%35%23%2
672
October1st to 15thNight
16%7%28%30%16%1
684
16th to endNight
19%12%31%27%8%
704
November1st to 15thNight
16%11%35%25%10%
700
16th to endNight
22%11%37%21%7%
858
December1st to 15thNight
25%11%37%22%4
900
16th to endNight
27%11%32%24%4
960
Page generated at 2017-10-07 13:07:48. Version ac04

Copyright 2017 A. Danko


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