MileOak Corner
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the MileOak Corner clear sky chart from 2005-11-05 to 2017-12-02.

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
27%
15218
18%
47769
8%
15187
38%
15187
19%
31517

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
17%
720
19%
2506
7%
716
33%
716
16%
1613
January16th to endNight
16%
768
19%
2686
6%
768
34%
768
15%
1749
February1st to 15thNight
15%
703
16%
2184
5%
701
28%
701
15%
1498
February16th to endNight
17%
631
21%
1893
6%
631
34%
631
16%
1279
March1st to 15thNight
16%
720
17%
2160
6%
720
28%
720
14%
1495
March16th to endNight
19%
768
22%
2013
7%
768
32%
768
21%
1359
April1st to 15thNight
17%
718
16%
1796
3%
718
25%
718
17%
1317
April16th to endNight
21%
630
17%
1710
3%
630
31%
630
18%
1180
May1st to 15thNight
18%
540
16%
1620
5%
540
28%
540
14%
1145
May16th to endNight
29%
376
12%
1498
9%
375
36%
375
13%
972
June1st to 15thNight
30%
360
13%
1440
10%
360
41%
360
15%
947
June16th to endNight
36%
360
12%
1440
11%
360
45%
360
19%
875
July1st to 15thNight
44%
340
12%
1360
14%
340
49%
340
20%
837
July16th to endNight
45%
376
13%
1418
15%
354
53%
354
20%
859
August1st to 15thNight
46%
483
16%
1554
12%
481
51%
481
25%
950
August16th to endNight
53%
764
20%
1910
10%
764
56%
764
31%
1248
September1st to 15thNight
40%
720
20%
1833
10%
720
45%
720
28%
1227
September16th to endNight
46%
717
27%
1980
16%
717
54%
717
30%
1220
October1st to 15thNight
36%
720
21%
2043
13%
720
45%
720
24%
1338
October16th to endNight
25%
768
17%
2466
7%
768
37%
768
19%
1632
November1st to 15thNight
26%
760
20%
2472
10%
760
40%
760
20%
1583
November16th to endNight
22%
780
21%
2553
8%
780
38%
780
18%
1658
December1st to 15thNight
20%
728
15%
2546
5%
728
33%
728
14%
1698
December16th to endNight
15%
768
17%
2688
5%
768
30%
768
12%
1838

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
16%6%25%43445%7%38%
48688
Night
17%6%25%42445%6%40%
47939
Cloud CoverDay
17%6%25%424447%39%
48698
Night
17%6%25%42445%6%40%
47944
TransparencyDay
44%6%12%21%13%1
48376
Night
44%5%12%21%14%1
47769
SeeingDay
20%18%26%20%9%3
6088
Night
18%22%27%23%7%
15219

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%7%24425%5%6%7%38%
1432
16th to endDay
14%8%25%42346%6%39%
1536
February1st to 15thDay
16%7%37%5%35%5%47%33%
1675
16th to endDay
15%8%37%5%24437%37%
1580
March1st to 15thDay
19%7%25%424447%34%
1790
16th to endDay
18%6%34424346%41%
2210
April1st to 15thDay
19%7%25%434346%37%
2152
16th to endDay
17%5%24434347%42%
2250
May1st to 15thDay
24%7%25%433446%32%
2341
16th to endDay
17%5%25%5%2445%7%38%
2618
June1st to 15thDay
22%7%3442445%7%33%
2520
16th to endDay
14%6%25%5%35%6%6%9%34%
2520
July1st to 15thDay
11%6%26%6%36%5%6%8%36%
2520
16th to endDay
12%436%5%35%5%6%8%37%
2654
August1st to 15thDay
13%5%25%5%46%5%6%7%38%
2381
16th to endDay
11%4246%3445%7%44%
2292
September1st to 15thDay
13%5%25%5%24446%45%
2127
16th to endDay
15%423413445%50%
1980
October1st to 15thDay
19%6%25%323346%42%
1914
16th to endDay
16%7%26%433435%41%
1758
November1st to 15thDay
17%8%34334246%41%
1716
16th to endDay
18%6%233245%45%43%
1735
December1st to 15thDay
19%5%35%324446%38%
1451
16th to endDay
22%8%245%2445%6%33%
1536
January1st to 15thNight
18%8%25%433346%39%
2506
16th to endNight
15%9%35%5%2336%5%38%
2686
February1st to 15thNight
15%7%36%6%35%45%5%36%
2183
16th to endNight
16%8%345%25%345%38%
1893
March1st to 15thNight
19%7%345%2445%6%35%
2147
16th to endNight
17%6%35%323346%42%
2013
April1st to 15thNight
18%9%35%6%34346%35%
1796
16th to endNight
22%6%25%423236%39%
1710
May1st to 15thNight
19%6%36%5%3435%5%35%
1620
16th to endNight
18%6%245%3445%8%37%
1496
June1st to 15thNight
22%5%25%42445%6%37%
1440
16th to endNight
15%5%25%32445%9%41%
1440
July1st to 15thNight
12%425%5%345%6%7%41%
1440
16th to endNight
10%5%25%5%35%6%6%9%38%
1514
August1st to 15thNight
10%5%15%4445%5%9%43%
1564
16th to endNight
11%415%43446%8%44%
1910
September1st to 15thNight
13%5%25%434445%45%
1833
16th to endNight
13%5%24314335%52%
1980
October1st to 15thNight
16%6%25%424445%44%
2043
16th to endNight
19%6%35%413445%39%
2466
November1st to 15thNight
17%7%24413345%44%
2472
16th to endNight
17%6%35%42344441%
2553
December1st to 15thNight
20%7%3442445%5%36%
2546
16th to endNight
21%7%25%42445%6%33%
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
16%7%245%35%35%6%39%
1432
16th to endDay
16%7%25%4235%6%6%39%
1536
February1st to 15thDay
16%7%36%6%35%45%7%32%
1675
16th to endDay
16%8%36%5%24346%37%
1580
March1st to 15thDay
20%8%35%434347%35%
1800
16th to endDay
18%7%24423335%42%
2210
April1st to 15thDay
19%7%35%5%24435%38%
2152
16th to endDay
18%5%14434346%43%
2250
May1st to 15thDay
25%7%25%423346%32%
2341
16th to endDay
18%5%3443445%7%39%
2618
June1st to 15thDay
23%7%3442435%7%33%
2520
16th to endDay
14%5%25%5%35%6%6%9%34%
2520
July1st to 15thDay
12%5%25%6%45%5%6%8%37%
2520
16th to endDay
13%435%5%35%5%5%9%37%
2654
August1st to 15thDay
13%5%26%5%45%5%5%7%37%
2381
16th to endDay
11%5%25%5%25%5%5%7%44%
2292
September1st to 15thDay
14%5%345%25%335%46%
2127
16th to endDay
15%31441335%5%50%
1980
October1st to 15thDay
18%6%24413346%42%
1914
16th to endDay
17%7%25%424435%41%
1758
November1st to 15thDay
19%7%34333346%41%
1716
16th to endDay
18%5%23324445%43%
1735
December1st to 15thDay
19%6%35%324437%38%
1451
16th to endDay
23%8%2442445%6%33%
1536
January1st to 15thNight
18%8%25%333345%39%
2506
16th to endNight
15%9%45%5%2345%6%38%
2686
February1st to 15thNight
15%7%36%5%35%45%5%36%
2176
16th to endNight
17%8%345%34445%38%
1893
March1st to 15thNight
20%6%35%5%2435%7%35%
2160
16th to endNight
18%6%25%423337%42%
2012
April1st to 15thNight
19%8%45%434345%35%
1796
16th to endNight
23%6%24423335%39%
1710
May1st to 15thNight
19%7%36%5%3435%5%35%
1620
16th to endNight
18%6%345%2445%8%36%
1496
June1st to 15thNight
22%5%245%23347%37%
1440
16th to endNight
15%5%2442345%8%42%
1440
July1st to 15thNight
13%4245%25%5%6%8%41%
1440
16th to endNight
10%5%35%4346%7%8%39%
1514
August1st to 15thNight
10%425%435%5%5%9%44%
1564
16th to endNight
12%4144345%6%8%44%
1910
September1st to 15thNight
14%5%25%334446%45%
1833
16th to endNight
15%424313245%51%
1980
October1st to 15thNight
17%5%25%423446%44%
2043
16th to endNight
19%6%25%5%23346%39%
2466
November1st to 15thNight
17%6%34323346%43%
2472
16th to endNight
17%7%35%423345%41%
2553
December1st to 15thNight
20%7%35%43345%5%37%
2546
16th to endNight
21%7%3442445%6%33%
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
43%5%15%23%10%2
1433
16th to endDay
42%5%14%24%11%1
1536
February1st to 15thDay
48%6%13%19%10%
1678
16th to endDay
47%5%10%21%13%2
1580
March1st to 15thDay
49%413%21%9%2
1800
16th to endDay
43%5%9%20%15%4
2210
April1st to 15thDay
48%311%19%15%2
2152
16th to endDay
42%49%21%18%3
2250
May1st to 15thDay
52%5%8%18%12%2
2341
16th to endDay
44%7%13%20%13%1
2622
June1st to 15thDay
49%6%13%19%10%1
2520
16th to endDay
42%9%14%20%12%
2520
July1st to 15thDay
44%7%11%21%14%1
2371
16th to endDay
41%7%16%20%13%2
2487
August1st to 15thDay
42%7%13%22%12%1
2367
16th to endDay
36%7%8%28%17%1
2292
September1st to 15thDay
39%5%11%22%18%2
2127
16th to endDay
35%48%24%24%2
1980
October1st to 15thDay
43%5%10%24%13%2
1914
16th to endDay
43%5%12%21%13%2
1758
November1st to 15thDay
44%5%12%21%13%2
1716
16th to endDay
41%5%11%25%14%2
1735
December1st to 15thDay
45%5%17%19%12%
1451
16th to endDay
50%6%15%17%9%
1536
January1st to 15thNight
46%314%21%11%2
2506
16th to endNight
45%5%11%22%12%2
2686
February1st to 15thNight
47%5%13%20%11%1
2184
16th to endNight
46%5%10%21%14%2
1893
March1st to 15thNight
48%5%11%19%12%2
2160
16th to endNight
42%410%20%16%5%
2013
April1st to 15thNight
50%49%17%15%1
1796
16th to endNight
46%48%19%17%4
1710
May1st to 15thNight
50%5%9%17%14%3
1620
16th to endNight
45%7%17%18%9%1
1498
June1st to 15thNight
47%6%14%19%11%
1440
16th to endNight
39%7%13%24%14%
1440
July1st to 15thNight
38%9%12%25%13%
1360
16th to endNight
39%7%16%23%11%2
1418
August1st to 15thNight
35%8%15%23%14%2
1554
16th to endNight
35%7%12%26%17%
1910
September1st to 15thNight
39%7%10%23%19%
1833
16th to endNight
35%47%23%26%2
1980
October1st to 15thNight
42%412%22%15%3
2043
16th to endNight
45%5%12%23%12%
2466
November1st to 15thNight
42%411%20%17%2
2472
16th to endNight
44%5%12%22%13%1
2553
December1st to 15thNight
47%6%15%20%10%
2546
16th to endNight
49%5%12%20%10%
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
16%31%31%16%3
60
16th to endDay
26%18%37%15%1
64
February1st to 15thDay
24%27%27%18%1
191
16th to endDay
18%28%33%15%2
239
March1st to 15thDay
30%25%24%18%2
270
16th to endDay
22%29%25%12%6%2
288
April1st to 15thDay
22%24%29%15%7%
270
16th to endDay
20%23%26%18%6%3
270
May1st to 15thDay
35%20%21%13%6%1
288
16th to endDay
19%19%29%19%8%2
331
June1st to 15thDay
22%20%24%20%10%2
315
16th to endDay
15%20%30%23%8%2
315
July1st to 15thDay
16%13%28%24%12%3
305
16th to endDay
15%14%23%26%16%3
326
August1st to 15thDay
13%12%23%30%13%7%
313
16th to endDay
12%9%23%26%19%8%
332
September1st to 15thDay
15%14%22%25%12%8%
315
16th to endDay
18%7%24%19%13%16%
314
October1st to 15thDay
23%9%21%23%13%7%
315
16th to endDay
19%21%27%22%8%
295
November1st to 15thDay
22%17%25%25%7%2
280
16th to endDay
23%20%27%18%8%2
265
December1st to 15thDay
14%28%33%14%7%1
63
16th to endDay
32%23%31%12%
64
January1st to 15thNight
18%28%31%19%2
720
16th to endNight
18%26%32%19%1
768
February1st to 15thNight
18%25%35%18%1
704
16th to endNight
20%29%30%17%2
631
March1st to 15thNight
23%30%26%17%1
720
16th to endNight
19%26%30%18%4
768
April1st to 15thNight
22%27%28%18%2
718
16th to endNight
20%28%25%19%5%
630
May1st to 15thNight
19%27%30%16%5%
540
16th to endNight
19%22%25%27%4
376
June1st to 15thNight
19%20%26%26%6%
360
16th to endNight
14%19%25%33%6%
360
July1st to 15thNight
12%13%23%37%12%
340
16th to endNight
11%17%19%39%10%1
376
August1st to 15thNight
12%12%23%38%12%
483
16th to endNight
11%10%18%37%20%2
764
September1st to 15thNight
15%12%26%30%13%
720
16th to endNight
15%13%18%28%19%4
717
October1st to 15thNight
20%14%25%28%10%1
720
16th to endNight
21%20%30%21%6%
768
November1st to 15thNight
18%22%28%20%8%
760
16th to endNight
15%27%29%19%6%
780
December1st to 15thNight
22%23%31%17%4
728
16th to endNight
23%29%28%17%1
768
Page generated at 2017-12-03 11:16:39. Version ac04

Copyright 2017 A. Danko


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