Cedarville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cedarville clear sky chart from 2005-11-05 to 2017-09-20.

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
63%
14962
22%
46891
21%
14937
65%
14937
34%
27048

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
54%
716
13%
2506
14%
716
57%
716
23%
1599
January16th to endNight
53%
768
20%
2580
22%
768
55%
768
25%
1630
February1st to 15thNight
54%
697
13%
2275
13%
696
56%
696
23%
1505
February16th to endNight
53%
632
18%
1895
17%
632
56%
632
28%
1207
March1st to 15thNight
48%
720
12%
2118
11%
720
51%
720
23%
1435
March16th to endNight
48%
768
15%
2022
11%
768
50%
768
27%
1371
April1st to 15thNight
52%
719
15%
1799
8%
719
54%
719
27%
1262
April16th to endNight
58%
720
19%
1800
11%
720
60%
720
41%
1094
May1st to 15thNight
61%
440
23%
1520
20%
440
65%
440
37%
783
May16th to endNight
58%
374
17%
1496
20%
374
63%
374
24%
858
June1st to 15thNight
68%
360
19%
1440
27%
360
72%
360
32%
738
June16th to endNight
78%
360
29%
1440
43%
360
83%
360
52%
554
July1st to 15thNight
89%
340
28%
1360
41%
340
90%
340
61%
473
July16th to endNight
90%
376
38%
1416
50%
354
92%
354
61%
503
August1st to 15thNight
86%
541
34%
1615
29%
539
87%
539
59%
748
August16th to endNight
87%
764
42%
1910
27%
764
88%
764
77%
880
September1st to 15thNight
86%
720
40%
1800
27%
720
88%
720
73%
851
September16th to endNight
79%
675
39%
1819
34%
675
81%
675
61%
887
October1st to 15thNight
69%
660
28%
1980
27%
660
74%
660
45%
1036
October16th to endNight
68%
704
24%
2161
26%
704
71%
704
39%
1196
November1st to 15thNight
60%
700
20%
2275
20%
700
62%
700
27%
1389
November16th to endNight
52%
720
15%
2456
15%
720
56%
720
25%
1504
December1st to 15thNight
52%
720
13%
2520
12%
720
55%
720
22%
1627
December16th to endNight
42%
768
14%
2688
15%
768
44%
768
16%
1918

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
45%25%5%3445%7%52%
47967
Night
45%25%5%35%5%5%8%48%
47063
TransparencyDay
31%410%20%19%13%
47638
Night
31%5%13%21%17%10%
46892
SeeingDay
7%9%24%28%21%9%
5679
Night
6%418%40%25%4
14975

By Month

Percentage Cloud Cover SW (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
26%38%9%5%8%9%7%9%28%
1432
16th to endDay
49%39%8%36%6%6%9%30%
1642
February1st to 15thDay
45%27%6%47%7%7%10%35%
1589
16th to endDay
37%47%7%37%6%6%11%34%
1579
March1st to 15thDay
410%48%7%47%6%6%8%31%
1839
16th to endDay
5%9%48%8%45%5%5%7%34%
2202
April1st to 15thDay
6%10%49%7%45%45%8%33%
2149
16th to endDay
6%7%35%6%3446%7%44%
2160
May1st to 15thDay
442442345%8%54%
2427
16th to endDay
9%6%36%5%35%5%46%43%
2615
June1st to 15thDay
7%425%43445%7%49%
2520
16th to endDay
32221223472%
2520
July1st to 15thDay
111213335%74%
2520
16th to endDay
11121323378%
2657
August1st to 15thDay
1113213435%72%
2334
16th to endDay
11111222381%
2292
September1st to 15thDay
111132233475%
2160
16th to endDay
3212223346%68%
1908
October1st to 15thDay
5%413423346%59%
1650
16th to endDay
45%25%5%24446%52%
1709
November1st to 15thDay
6%6%36%5%446%7%9%40%
1584
16th to endDay
46%35%7%45%6%6%9%38%
1503
December1st to 15thDay
48%47%8%37%5%6%9%33%
1440
16th to endDay
5%6%5%11%11%5%7%6%7%7%25%
1536
January1st to 15thNight
37%37%7%47%7%8%11%31%
2506
16th to endNight
310%48%7%36%5%5%8%37%
2580
February1st to 15thNight
37%36%7%47%7%8%11%30%
2263
16th to endNight
28%47%7%46%6%6%8%37%
1895
March1st to 15thNight
48%46%8%46%5%7%10%32%
2118
16th to endNight
5%9%37%6%35%5%6%9%37%
2022
April1st to 15thNight
47%36%7%47%6%7%9%35%
1799
16th to endNight
6%6%3342336%7%53%
1800
May1st to 15thNight
5%314424447%56%
1520
16th to endNight
6%6%36%5%35%45%7%45%
1496
June1st to 15thNight
7%5%2432445%6%52%
1440
16th to endNight
2212322235%72%
1440
July1st to 15thNight
1111345%5%75%
1440
16th to endNight
121233477%
1512
August1st to 15thNight
2212223235%71%
1623
16th to endNight
11111235%80%
1910
September1st to 15thNight
111212235%79%
1800
16th to endNight
221121335%6%69%
1819
October1st to 15thNight
5%5%13323345%61%
1980
16th to endNight
45%236%33449%52%
2161
November1st to 15thNight
6%6%36%6%35%6%6%7%42%
2275
16th to endNight
26%46%7%36%5%6%9%39%
2456
December1st to 15thNight
6%7%36%6%35%6%7%11%34%
2520
16th to endNight
6%10%49%8%47%7%7%9%24%
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
44%8%19%17%7%1
1432
16th to endDay
46%7%12%20%9%4
1642
February1st to 15thDay
40%8%17%22%9%1
1589
16th to endDay
40%6%18%26%5%2
1579
March1st to 15thDay
46%8%13%20%10%1
1839
16th to endDay
45%6%20%16%8%2
2202
April1st to 15thDay
48%5%13%21%9%
2149
16th to endDay
38%414%26%14%2
2160
May1st to 15thDay
27%311%29%22%5%
2427
16th to endDay
41%410%23%16%3
2619
June1st to 15thDay
33%410%20%22%8%
2520
16th to endDay
16%25%19%39%16%
2520
July1st to 15thDay
12%2314%29%36%
2371
16th to endDay
12%2110%26%46%
2490
August1st to 15thDay
15%3215%26%36%
2317
16th to endDay
10%1214%35%36%
2292
September1st to 15thDay
13%2213%32%34%
2160
16th to endDay
18%26%25%27%18%
1908
October1st to 15thDay
25%39%28%23%10%
1650
16th to endDay
31%412%25%18%7%
1709
November1st to 15thDay
38%5%17%22%13%3
1584
16th to endDay
37%6%15%24%13%2
1503
December1st to 15thDay
45%7%16%21%9%
1440
16th to endDay
51%8%14%18%7%
1536
January1st to 15thNight
39%8%19%21%8%1
2506
16th to endNight
42%413%20%12%6%
2580
February1st to 15thNight
41%9%18%17%10%2
2275
16th to endNight
37%7%20%24%7%1
1895
March1st to 15thNight
43%7%18%17%10%2
2118
16th to endNight
41%6%19%21%9%1
2022
April1st to 15thNight
41%8%17%22%8%1
1799
16th to endNight
29%5%18%30%12%3
1800
May1st to 15thNight
27%413%27%23%4
1521
16th to endNight
37%5%14%26%12%3
1496
June1st to 15thNight
29%5%13%24%21%5%
1440
16th to endNight
15%26%22%38%14%
1440
July1st to 15thNight
9%35%16%32%31%
1360
16th to endNight
10%2312%24%46%
1416
August1st to 15thNight
15%2417%26%32%
1615
16th to endNight
8%2218%34%34%
1910
September1st to 15thNight
9%2314%32%36%
1800
16th to endNight
15%36%27%26%21%
1819
October1st to 15thNight
24%310%27%24%9%
1980
16th to endNight
29%414%26%19%6%
2161
November1st to 15thNight
38%6%16%22%12%3
2275
16th to endNight
38%6%16%20%15%2
2456
December1st to 15thNight
40%8%17%21%11%
2520
16th to endNight
51%7%12%19%8%
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
13%5%21%41%15%3
60
16th to endDay
11%5%21%30%21%10%
170
February1st to 15thDay
5%7%25%34%20%5%
239
16th to endDay
8%12%28%33%15%1
238
March1st to 15thDay
10%11%32%26%14%2
270
16th to endDay
12%17%29%29%9%3
288
April1st to 15thDay
11%17%24%25%13%6%
269
16th to endDay
10%16%30%23%15%4
270
May1st to 15thDay
8%15%26%24%20%4
288
16th to endDay
13%9%17%25%19%15%
330
June1st to 15thDay
9%11%24%24%21%7%
315
16th to endDay
48%27%25%20%14%
315
July1st to 15thDay
3317%29%32%13%
305
16th to endDay
1319%36%25%11%
327
August1st to 15thDay
3123%32%25%13%
315
16th to endDay
25%25%24%25%17%
332
September1st to 15thDay
2218%27%31%17%
315
16th to endDay
48%21%29%24%11%
272
October1st to 15thDay
9%14%21%24%23%8%
255
16th to endDay
10%11%26%27%16%8%
221
November1st to 15thDay
8%312%31%33%11%
90
16th to endDay
5%438%33%12%5%
71
December1st to 15thDay
5%10%26%50%6%1
60
16th to endDay
46%14%35%32%6%
64
January1st to 15thNight
5%322%42%21%3
720
16th to endNight
9%322%33%26%4
768
February1st to 15thNight
6%423%45%16%2
704
16th to endNight
6%6%21%44%17%3
632
March1st to 15thNight
7%7%23%36%20%3
720
16th to endNight
9%7%26%38%17%1
768
April1st to 15thNight
5%8%24%40%18%1
719
16th to endNight
9%420%36%23%5%
720
May1st to 15thNight
7%423%38%24%2
441
16th to endNight
9%316%37%29%4
375
June1st to 15thNight
8%211%48%26%1
360
16th to endNight
312%49%33%1
360
July1st to 15thNight
15%47%45%
340
16th to endNight
1453%38%1
376
August1st to 15thNight
2446%42%3
541
16th to endNight
27%44%40%4
764
September1st to 15thNight
27%34%45%9%
720
16th to endNight
429%36%36%10%
675
October1st to 15thNight
6%315%40%28%5%
660
16th to endNight
7%313%41%24%9%
704
November1st to 15thNight
9%318%44%21%4
700
16th to endNight
45%26%40%16%5%
720
December1st to 15thNight
7%6%23%40%18%3
720
16th to endNight
10%7%29%36%13%2
768
Page generated at 2017-09-21 04:18:22. Version ac04

Copyright 2017 A. Danko


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