Herron Observing Field
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Herron Observing Field clear sky chart from 2005-11-05 to 2017-10-31.

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
47%
15648
24%
47437
16%
15607
56%
15607
29%
28753

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
24%
720
23%
2327
9%
716
41%
716
21%
1441
January16th to endNight
26%
768
25%
2443
11%
768
43%
768
21%
1536
February1st to 15thNight
29%
702
26%
2112
10%
701
45%
701
26%
1282
February16th to endNight
24%
631
25%
1893
9%
631
39%
631
24%
1185
March1st to 15thNight
29%
720
23%
2070
11%
720
40%
720
26%
1309
March16th to endNight
39%
768
22%
2112
13%
768
45%
768
31%
1303
April1st to 15thNight
42%
623
26%
1881
16%
623
53%
623
32%
1071
April16th to endNight
50%
540
27%
1707
18%
540
59%
540
34%
964
May1st to 15thNight
50%
540
21%
1620
13%
540
58%
540
31%
985
May16th to endNight
63%
561
21%
1682
14%
561
68%
561
34%
991
June1st to 15thNight
72%
540
17%
1620
15%
540
73%
540
32%
1000
June16th to endNight
76%
540
18%
1620
15%
540
77%
540
37%
941
July1st to 15thNight
70%
510
14%
1530
13%
510
71%
510
30%
970
July16th to endNight
72%
564
17%
1595
16%
531
74%
531
30%
996
August1st to 15thNight
73%
539
20%
1646
21%
536
74%
536
29%
1021
August16th to endNight
63%
573
20%
1910
22%
573
64%
573
23%
1239
September1st to 15thNight
62%
696
20%
1956
18%
696
64%
696
30%
1275
September16th to endNight
62%
717
27%
1980
20%
717
66%
717
34%
1218
October1st to 15thNight
54%
720
34%
1981
25%
720
62%
720
41%
1134
October16th to endNight
51%
768
36%
2303
27%
768
65%
768
38%
1256
November1st to 15thNight
49%
700
31%
2273
25%
700
61%
700
35%
1211
November16th to endNight
38%
720
28%
2340
17%
720
52%
720
29%
1347
December1st to 15thNight
31%
720
24%
2340
14%
720
45%
720
25%
1419
December16th to endNight
30%
768
20%
2496
13%
768
40%
768
19%
1659

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%7%40%
48301
Night
12%5%2442445%7%45%
47636
TransparencyDay
39%411%21%17%4
48002
Night
37%410%21%20%5%
47439
SeeingDay
16%6%18%22%21%13%
5534
Night
15%8%21%28%22%4
15652

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
18%7%34224345%41%
1611
16th to endDay
19%6%23323446%43%
1779
February1st to 15thDay
16%7%24324448%41%
1750
16th to endDay
20%5%24424345%41%
1580
March1st to 15thDay
16%6%25%42445%6%40%
1888
16th to endDay
17%4245%34447%41%
2111
April1st to 15thDay
12%6%25%42345%6%44%
2076
16th to endDay
11%3244345%48%46%
2252
May1st to 15thDay
12%5%245%25%46%7%42%
2331
16th to endDay
10%425%6%346%6%8%40%
2431
June1st to 15thDay
8%5%26%6%36%6%8%10%34%
2340
16th to endDay
6%214447%6%8%12%41%
2340
July1st to 15thDay
10%5%25%6%5%8%7%7%10%29%
2340
16th to endDay
8%5%35%7%48%8%8%9%30%
2465
August1st to 15thDay
9%5%25%6%5%6%7%8%10%32%
2299
16th to endDay
12%6%36%8%5%6%7%7%8%26%
2292
September1st to 15thDay
12%6%25%5%346%6%8%37%
1989
16th to endDay
15%5%134245%5%6%44%
1980
October1st to 15thDay
13%5%13323236%54%
1977
16th to endDay
12%42432224358%
1920
November1st to 15thDay
14%413312345%55%
1582
16th to endDay
15%5%14424345%48%
1620
December1st to 15thDay
19%6%26%42345%5%40%
1620
16th to endDay
26%7%3432433435%
1728
January1st to 15thNight
19%6%34323346%42%
2327
16th to endNight
17%7%34323345%42%
2443
February1st to 15thNight
15%5%24324346%47%
2103
16th to endNight
17%5%25%414445%44%
1893
March1st to 15thNight
14%6%24424346%45%
2070
16th to endNight
12%5%24424446%47%
2112
April1st to 15thNight
12%41332345%7%49%
1881
16th to endNight
9%423425%448%49%
1707
May1st to 15thNight
10%424446%5%5%7%45%
1619
16th to endNight
6%4245%35%47%9%46%
1682
June1st to 15thNight
5%4245%45%6%8%11%40%
1620
16th to endNight
4315%435%6%8%12%43%
1620
July1st to 15thNight
6%5%25%6%46%6%7%11%37%
1620
16th to endNight
5%425%6%26%7%8%11%38%
1703
August1st to 15thNight
6%425%5%35%6%6%11%41%
1657
16th to endNight
10%5%26%7%35%5%6%10%35%
1910
September1st to 15thNight
10%5%25%5%36%5%6%8%40%
1956
16th to endNight
12%3135%3445%6%48%
1980
October1st to 15thNight
10%5%23312347%55%
1981
16th to endNight
9%42332322459%
2303
November1st to 15thNight
11%5%13313236%57%
2273
16th to endNight
15%6%23323345%50%
2340
December1st to 15thNight
15%7%25%423347%43%
2340
16th to endNight
22%7%25%423346%35%
2496

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%38%16%23%4
1612
16th to endDay
43%26%20%21%6%
1779
February1st to 15thDay
40%27%22%22%3
1752
16th to endDay
44%26%20%19%5%
1580
March1st to 15thDay
43%38%19%19%5%
1888
16th to endDay
41%312%23%16%3
2112
April1st to 15thDay
38%210%22%20%4
2076
16th to endDay
34%48%25%21%4
2252
May1st to 15thDay
38%313%22%19%3
2331
16th to endDay
37%5%15%25%14%2
2435
June1st to 15thDay
39%6%18%25%8%1
2340
16th to endDay
30%6%17%28%14%2
2340
July1st to 15thDay
41%8%20%20%8%1
2201
16th to endDay
40%8%19%20%9%1
2310
August1st to 15thDay
40%8%17%22%9%1
2286
16th to endDay
49%6%14%18%10%1
2292
September1st to 15thDay
41%5%13%20%15%3
1989
16th to endDay
38%411%20%21%4
1980
October1st to 15thDay
32%29%19%26%8%
1977
16th to endDay
30%15%19%31%11%
1920
November1st to 15thDay
32%25%16%33%9%
1582
16th to endDay
38%35%17%27%7%
1620
December1st to 15thDay
45%28%21%15%7%
1620
16th to endDay
52%27%17%14%5%
1728
January1st to 15thNight
42%27%19%23%5%
2327
16th to endNight
43%15%20%22%6%
2443
February1st to 15thNight
39%16%21%21%8%
2112
16th to endNight
41%2421%24%5%
1893
March1st to 15thNight
39%39%20%18%8%
2070
16th to endNight
36%310%26%18%4
2112
April1st to 15thNight
33%29%24%23%6%
1881
16th to endNight
32%39%24%21%7%
1707
May1st to 15thNight
36%413%21%20%2
1620
16th to endNight
32%5%15%27%14%3
1684
June1st to 15thNight
32%8%20%25%10%1
1620
16th to endNight
29%7%20%23%16%2
1620
July1st to 15thNight
36%7%20%23%9%2
1530
16th to endNight
34%8%21%20%12%2
1595
August1st to 15thNight
34%8%16%26%12%1
1646
16th to endNight
41%7%17%18%14%1
1910
September1st to 15thNight
39%5%14%20%15%4
1956
16th to endNight
35%411%23%19%5%
1980
October1st to 15thNight
30%210%20%28%7%
1981
16th to endNight
29%1317%33%13%
2303
November1st to 15thNight
30%2416%32%12%
2273
16th to endNight
36%25%18%27%9%
2340
December1st to 15thNight
40%29%21%18%7%
2340
16th to endNight
49%28%17%18%4
2496

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
25%12%41%14%6%
90
16th to endDay
22%29%39%44
96
February1st to 15thDay
24%22%37%13%2
90
16th to endDay
30%14%43%11%
81
March1st to 15thDay
24%14%32%20%6%1
178
16th to endDay
18%10%33%23%12%2
288
April1st to 15thDay
19%10%30%21%17%2
270
16th to endDay
15%423%31%21%4
270
May1st to 15thDay
15%8%27%18%17%12%
288
16th to endDay
14%415%30%22%13%
331
June1st to 15thDay
11%18%26%26%26%
315
16th to endDay
10%11%24%24%28%
315
July1st to 15thDay
10%8%22%27%30%
305
16th to endDay
11%25%14%38%29%
326
August1st to 15thDay
17%1423%29%23%
313
16th to endDay
16%25%25%29%20%
332
September1st to 15thDay
15%6%8%21%26%21%
315
16th to endDay
17%210%30%27%11%
314
October1st to 15thDay
18%222%25%25%5%
315
16th to endDay
14%8%19%25%25%6%
336
November1st to 15thDay
30%15%20%18%13%2
90
16th to endDay
12%12%36%23%13%2
90
December1st to 15thDay
26%15%34%21%2
90
16th to endDay
37%12%34%12%3
96
January1st to 15thNight
24%15%30%22%7%
720
16th to endNight
22%16%30%27%4
768
February1st to 15thNight
20%14%32%28%4
704
16th to endNight
19%17%34%24%3
631
March1st to 15thNight
18%13%35%25%6%
720
16th to endNight
16%10%28%31%13%
768
April1st to 15thNight
15%10%28%28%16%
623
16th to endNight
12%6%26%33%18%2
540
May1st to 15thNight
11%7%23%31%24%2
540
16th to endNight
9%214%32%32%7%
563
June1st to 15thNight
7%28%33%37%11%
540
16th to endNight
5%7%34%39%12%
540
July1st to 15thNight
6%3422%48%13%
510
16th to endNight
5%3419%52%14%
564
August1st to 15thNight
8%25%27%46%10%
539
16th to endNight
13%27%24%41%10%
573
September1st to 15thNight
13%29%24%40%10%
696
16th to endNight
14%113%33%33%3
717
October1st to 15thNight
14%422%29%23%6%
720
16th to endNight
11%8%22%31%21%4
768
November1st to 15thNight
14%7%24%29%22%2
700
16th to endNight
19%12%26%26%14%
720
December1st to 15thNight
18%12%30%27%10%
720
16th to endNight
26%11%27%26%7%
768
Page generated at 2017-11-01 17:23:37. Version ac04

Copyright 2017 A. Danko


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