Millers Ferry
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Millers Ferry clear sky chart from 2005-11-06 to 2024-01-14.

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
51%
23402
23%
74448
17%
23347
58%
23347
28%
45271

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 10thNight
29%
760
24%
2448
11%
757
44%
757
24%
1495
January11th to 20thNight
32%
736
27%
2208
15%
736
44%
736
23%
1421
January21st to endNight
28%
792
28%
2376
12%
792
42%
792
24%
1533
February1st to 10thNight
32%
720
23%
2160
12%
720
42%
720
25%
1391
February11th to 20thNight
30%
703
23%
2099
10%
700
41%
700
24%
1349
February21st to endNight
26%
592
21%
1776
9%
592
35%
592
22%
1191
March1st to 10thNight
33%
720
25%
2160
13%
720
42%
720
29%
1286
March11th to 20thNight
33%
720
21%
2093
11%
720
41%
720
25%
1354
March21st to endNight
40%
646
26%
2032
15%
646
50%
646
29%
1191
April1st to 10thNight
41%
540
25%
1800
17%
540
51%
540
29%
1035
April11th to 20thNight
42%
533
25%
1775
20%
533
52%
533
29%
1031
April21st to endNight
56%
540
30%
1800
24%
540
68%
540
38%
939
May1st to 10thNight
55%
540
25%
1755
20%
540
64%
540
38%
943
May11th to 20thNight
59%
531
19%
1592
14%
531
64%
531
31%
988
May21st to endNight
69%
582
22%
1744
20%
582
72%
582
32%
1078
June1st to 10thNight
69%
540
14%
1620
14%
540
70%
540
27%
1065
June11th to 20thNight
77%
540
19%
1620
18%
540
79%
540
38%
962
June21st to endNight
69%
540
14%
1620
13%
540
70%
540
28%
1040
July1st to 10thNight
77%
525
11%
1575
11%
525
77%
525
24%
1065
July11th to 20thNight
76%
522
12%
1569
12%
522
76%
522
27%
1024
July21st to endNight
76%
591
14%
1858
15%
558
78%
558
27%
1157
August1st to 10thNight
77%
537
11%
1778
13%
534
78%
534
25%
1124
August11th to 20thNight
73%
534
14%
1776
18%
534
73%
534
21%
1189
August21st to endNight
67%
594
19%
1980
23%
594
67%
594
21%
1338
September1st to 10thNight
68%
544
20%
1804
22%
544
68%
544
24%
1164
September11th to 20thNight
65%
720
21%
1980
17%
720
67%
720
30%
1276
September21st to endNight
65%
720
28%
1980
22%
720
68%
720
36%
1193
October1st to 10thNight
62%
720
29%
1980
21%
720
67%
720
42%
1136
October11th to 20thNight
59%
720
37%
1980
27%
720
67%
720
43%
1111
October21st to endNight
53%
792
32%
2429
28%
792
60%
792
35%
1372
November1st to 10thNight
56%
740
29%
2406
26%
740
64%
740
36%
1269
November11th to 20thNight
48%
760
32%
2470
24%
760
60%
760
35%
1336
November21st to endNight
45%
760
27%
2470
21%
760
55%
760
28%
1458
December1st to 10thNight
40%
760
27%
2470
19%
760
52%
760
27%
1482
December11th to 20thNight
34%
759
24%
2896
15%
758
45%
758
21%
1738
December21st to endNight
33%
829
15%
4369
14%
817
42%
817
14%
2547

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
11%6%25%6%35%5%6%8%43%
74791
Night
11%5%25%5%345%6%8%46%
74977
TransparencyDay
39%7%11%19%19%6%
74526
Night
36%7%11%18%20%8%
74761
SeeingDay
13%9%20%25%22%11%
13378
Night
13%7%21%31%23%5%
23412

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 10thDay
17%8%2432345%6%43%
1713
11th to 20thDay
14%8%36%5%2445%6%44%
1830
21st to endDay
16%7%343235%5%5%46%
1980
February1st to 10thDay
16%8%36%5%3445%7%39%
1800
11th to 20thDay
19%6%346%34345%43%
1748
21st to endDay
18%7%26%44445%5%39%
1480
March1st to 10thDay
13%6%25%5%345%5%6%46%
1800
11th to 20thDay
16%6%25%6%445%6%6%39%
1867
21st to endDay
11%6%36%6%35%5%5%7%45%
2337
April1st to 10thDay
12%5%25%5%346%5%7%46%
2160
11th to 20thDay
11%5%25%6%35%45%7%45%
2134
21st to endDay
7%4245%35%447%54%
2160
May1st to 10thDay
10%4245%3445%8%51%
2204
11th to 20thDay
6%5%27%5%46%7%6%8%44%
2301
21st to endDay
8%425%6%36%6%6%9%44%
2531
June1st to 10thDay
8%6%37%6%5%6%7%7%10%36%
2340
11th to 20thDay
6%325%6%47%6%8%12%40%
2340
21st to endDay
6%5%26%7%5%7%6%8%12%36%
2340
July1st to 10thDay
8%436%9%5%8%8%9%11%29%
2340
11th to 20thDay
8%5%26%7%5%9%8%9%10%31%
2332
21st to endDay
6%436%7%5%8%9%8%11%33%
2350
August1st to 10thDay
5%326%7%5%9%7%10%11%36%
2148
11th to 20thDay
10%5%35%8%5%7%7%8%10%33%
2125
21st to endDay
11%6%26%7%48%6%7%8%34%
2376
September1st to 10thDay
10%5%36%7%45%6%6%9%40%
2138
11th to 20thDay
12%6%25%6%45%46%7%42%
1980
21st to endDay
9%5%25%5%3445%7%51%
1980
October1st to 10thDay
7%5%245%34447%54%
1980
11th to 20thDay
10%43442445%7%53%
1980
21st to endDay
12%5%25%333446%53%
1918
November1st to 10thDay
10%424324446%57%
1672
11th to 20thDay
13%5%3342435%6%52%
1710
21st to endDay
14%5%245%3445%7%48%
1710
December1st to 10thDay
15%7%35%5%3445%6%44%
1710
11th to 20thDay
16%9%36%5%235%4443%
2153
21st to endDay
16%9%35%5%34445%41%
3124
January1st to 10thNight
16%6%345%23445%48%
2448
11th to 20thNight
16%8%35%424346%44%
2208
21st to endNight
18%6%35%433446%44%
2376
February1st to 10thNight
14%7%36%5%3445%7%41%
2160
11th to 20thNight
20%7%2441334447%
2098
21st to endNight
17%8%36%43445%6%39%
1776
March1st to 10thNight
14%6%24433447%49%
2160
11th to 20thNight
14%5%45%5%35%5%5%6%43%
2093
21st to endNight
13%5%244345%5%7%49%
2032
April1st to 10thNight
10%5%35%43446%8%48%
1800
11th to 20thNight
13%5%2443447%8%47%
1775
21st to endNight
7%323435%46%7%57%
1800
May1st to 10thNight
9%42442345%8%56%
1755
11th to 20thNight
7%5%25%6%46%6%7%10%43%
1592
21st to endNight
7%425%5%46%6%7%11%44%
1744
June1st to 10thNight
7%5%36%6%46%6%8%13%36%
1620
11th to 20thNight
5%2235%35%8%9%12%44%
1620
21st to endNight
6%5%36%7%46%6%7%12%39%
1620
July1st to 10thNight
5%435%6%46%8%9%14%35%
1620
11th to 20thNight
5%426%6%46%7%8%13%37%
1623
21st to endNight
4426%7%47%8%10%11%39%
1968
August1st to 10thNight
4326%7%47%8%8%15%37%
1790
11th to 20thNight
7%425%7%5%7%7%9%12%34%
1776
21st to endNight
9%6%36%6%46%6%7%9%38%
1980
September1st to 10thNight
9%5%36%6%46%6%6%9%40%
1804
11th to 20thNight
11%5%15%435%6%6%9%44%
1980
21st to endNight
7%426%5%345%6%8%50%
1980
October1st to 10thNight
7%42443446%7%55%
1980
11th to 20thNight
10%424323446%58%
1980
21st to endNight
11%5%24433235%57%
2429
November1st to 10thNight
9%424323446%59%
2406
11th to 20thNight
13%424323446%56%
2470
21st to endNight
13%6%35%425%45%6%48%
2470
December1st to 10thNight
15%6%25%42445%6%48%
2470
11th to 20thNight
17%7%34423345%47%
3042
21st to endNight
16%7%35%5%345%5%7%40%
4532

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 10thDay
41%46%18%25%6%
1714
11th to 20thDay
42%5%6%16%24%8%
1830
21st to endDay
40%45%17%25%8%
1980
February1st to 10thDay
44%47%17%20%7%
1800
11th to 20thDay
44%45%17%23%8%
1758
21st to endDay
46%5%7%15%17%10%
1480
March1st to 10thDay
38%48%19%22%10%
1800
11th to 20thDay
45%5%10%15%18%7%
1867
21st to endDay
39%5%8%19%23%6%
2337
April1st to 10thDay
36%5%10%20%20%8%
2160
11th to 20thDay
38%48%20%21%9%
2134
21st to endDay
30%5%9%22%29%5%
2160
May1st to 10thDay
33%5%9%23%25%6%
2204
11th to 20thDay
34%9%15%22%17%2
2305
21st to endDay
35%8%12%22%21%3
2531
June1st to 10thDay
42%9%13%23%11%2
2340
11th to 20thDay
33%10%17%25%13%3
2340
21st to endDay
39%10%18%21%11%2
2340
July1st to 10thDay
43%12%21%14%8%1
2275
11th to 20thDay
41%13%21%17%7%1
2263
21st to endDay
39%13%21%21%6%1
2219
August1st to 10thDay
37%12%22%21%8%
2136
11th to 20thDay
43%12%18%16%9%3
2125
21st to endDay
45%9%15%17%10%3
2376
September1st to 10thDay
39%9%13%17%17%6%
2138
11th to 20thDay
40%7%12%18%18%5%
1980
21st to endDay
33%6%9%20%23%8%
1980
October1st to 10thDay
30%5%10%17%25%13%
1980
11th to 20thDay
30%46%21%27%11%
1980
21st to endDay
33%4417%29%14%
1918
November1st to 10thDay
30%46%19%29%12%
1672
11th to 20thDay
33%46%18%27%13%
1710
21st to endDay
36%49%18%23%10%
1710
December1st to 10thDay
41%5%8%19%20%6%
1710
11th to 20thDay
46%36%14%26%5%
2150
21st to endDay
45%5%5%20%20%4
3124
January1st to 10thNight
40%46%17%26%7%
2448
11th to 20thNight
42%47%17%23%7%
2208
21st to endNight
43%4414%27%9%
2376
February1st to 10thNight
43%48%17%19%10%
2160
11th to 20thNight
42%45%15%22%11%
2099
21st to endNight
45%5%7%16%15%12%
1776
March1st to 10thNight
36%49%16%22%13%
2160
11th to 20thNight
41%5%9%17%18%9%
2093
21st to endNight
33%6%9%19%24%8%
2032
April1st to 10thNight
34%5%13%17%20%11%
1800
11th to 20thNight
35%5%8%18%23%10%
1775
21st to endNight
26%5%9%25%26%9%
1800
May1st to 10thNight
28%5%11%22%25%8%
1755
11th to 20thNight
35%8%16%20%17%4
1593
21st to endNight
31%11%13%20%21%4
1745
June1st to 10thNight
37%11%18%18%15%1
1620
11th to 20thNight
27%10%20%26%15%3
1620
21st to endNight
36%9%21%17%12%4
1620
July1st to 10thNight
36%15%24%15%7%2
1575
11th to 20thNight
33%14%30%17%6%1
1569
21st to endNight
32%13%25%22%7%
1858
August1st to 10thNight
31%16%24%21%7%1
1778
11th to 20thNight
37%15%18%16%9%4
1776
21st to endNight
40%13%15%16%13%4
1980
September1st to 10thNight
38%11%14%16%15%7%
1804
11th to 20thNight
35%9%12%18%18%7%
1980
21st to endNight
32%6%10%20%21%10%
1980
October1st to 10thNight
27%6%9%19%23%16%
1980
11th to 20thNight
26%5%7%21%28%13%
1980
21st to endNight
32%3416%27%18%
2429
November1st to 10thNight
28%47%17%27%17%
2406
11th to 20thNight
31%35%20%28%14%
2470
21st to endNight
37%46%19%21%13%
2470
December1st to 10thNight
38%410%20%23%5%
2470
11th to 20thNight
41%36%13%30%7%
3044
21st to endNight
42%5%7%19%24%3
4532

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 10thDay
21%23%37%14%31
270
11th to 20thDay
19%20%31%18%10%2
249
21st to endDay
18%26%35%17%21
264
February1st to 10thDay
22%23%34%18%3
240
11th to 20thDay
32%16%35%14%2
240
21st to endDay
20%23%40%15%3
198
March1st to 10thDay
19%21%41%13%5%
240
11th to 20thDay
20%21%29%21%8%1
307
21st to endDay
18%17%32%22%10%
462
April1st to 10thDay
16%15%28%27%12%2
420
11th to 20thDay
15%13%32%26%13%2
412
21st to endDay
10%14%26%28%18%4
420
May1st to 10thDay
9%11%24%30%22%4
423
11th to 20thDay
7%419%34%24%12%
447
21st to endDay
11%415%30%25%15%
485
June1st to 10thDay
11%312%33%26%14%
450
11th to 20thDay
9%310%28%32%18%
450
21st to endDay
7%312%29%30%20%
450
July1st to 10thDay
8%26%24%38%23%
445
11th to 20thDay
7%1418%40%30%
444
21st to endDay
5%16%24%40%24%
488
August1st to 10thDay
6%19%17%35%31%
446
11th to 20thDay
8%15%21%35%29%
439
21st to endDay
13%36%20%32%25%
495
September1st to 10thDay
9%37%27%34%19%
450
11th to 20thDay
13%29%26%36%14%
450
21st to endDay
10%313%28%32%14%
450
October1st to 10thDay
11%420%34%22%9%
450
11th to 20thDay
12%6%18%31%27%6%
450
21st to endDay
21%13%21%28%13%4
297
November1st to 10thDay
17%7%27%30%14%4
270
11th to 20thDay
17%13%34%24%10%2
270
21st to endDay
13%16%32%30%8%2
270
December1st to 10thDay
23%14%34%19%9%1
270
11th to 20thDay
27%15%31%19%6%1
270
21st to endDay
22%18%31%22%6%1
297
January1st to 10thNight
19%16%31%29%5%
760
11th to 20thNight
19%15%27%31%8%1
736
21st to endNight
22%13%33%28%4
792
February1st to 10thNight
18%13%32%32%6%
720
11th to 20thNight
24%14%30%26%6%
703
21st to endNight
19%16%36%26%4
592
March1st to 10thNight
16%13%34%30%7%
720
11th to 20thNight
14%14%35%26%10%
720
21st to endNight
15%11%33%30%11%
646
April1st to 10thNight
14%11%31%32%13%
540
11th to 20thNight
15%8%30%30%17%1
533
21st to endNight
8%8%26%41%16%1
540
May1st to 10thNight
10%5%25%35%22%3
540
11th to 20thNight
9%219%39%26%5%
531
21st to endNight
9%111%35%36%7%
584
June1st to 10thNight
9%18%38%38%6%
540
11th to 20thNight
6%17%28%45%12%
540
21st to endNight
6%19%28%42%13%
540
July1st to 10thNight
6%2227%45%18%
525
11th to 20thNight
7%1319%49%21%
522
21st to endNight
425%26%50%14%
591
August1st to 10thNight
5%1322%49%20%
537
11th to 20thNight
8%1327%46%14%
534
21st to endNight
11%27%23%40%18%
594
September1st to 10thNight
10%36%24%43%14%
544
11th to 20thNight
13%29%33%37%6%
720
21st to endNight
10%213%31%40%5%
720
October1st to 10thNight
9%221%35%29%5%
720
11th to 20thNight
12%5%20%32%28%3
720
21st to endNight
13%7%21%34%22%3
792
November1st to 10thNight
10%7%21%36%22%3
740
11th to 20thNight
15%8%25%36%15%1
760
21st to endNight
15%9%25%37%12%1
760
December1st to 10thNight
18%10%28%31%13%1
760
11th to 20thNight
22%7%31%30%10%
760
21st to endNight
22%11%29%30%8%
836
Page generated at 2024-01-11 12:32:03. Version ac07

Copyright 2024 Attilla Danko


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