Middle Fork River Forest Preserve
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Middle Fork River Forest Preserve clear sky chart from 2005-11-06 to 2024-02-25.

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
37%
24659
18%
80511
12%
24555
44%
24555
21%
54316

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
19%
943
11%
4390
5%
926
28%
926
10%
3183
January11th to 20thNight
18%
949
11%
4386
4%
930
25%
930
8%
3510
January21st to endNight
19%
1041
8%
4683
4%
1023
26%
1023
9%
3669
February1st to 10thNight
19%
851
13%
2371
4%
851
26%
851
16%
1782
February11th to 20thNight
23%
740
17%
2219
7%
740
32%
740
18%
1522
February21st to endNight
18%
611
16%
1831
4%
611
28%
611
16%
1311
March1st to 10thNight
25%
720
15%
2160
8%
720
32%
720
18%
1504
March11th to 20thNight
29%
712
19%
2122
9%
712
38%
712
23%
1397
March21st to endNight
25%
594
15%
1980
7%
594
36%
594
17%
1406
April1st to 10thNight
30%
540
19%
1800
11%
540
42%
540
22%
1161
April11th to 20thNight
32%
533
21%
1775
15%
533
42%
533
23%
1134
April21st to endNight
29%
540
16%
1728
8%
540
38%
540
19%
1190
May1st to 10thNight
35%
540
16%
1620
9%
540
41%
540
23%
1099
May11th to 20thNight
42%
531
17%
1551
11%
531
47%
531
26%
1037
May21st to endNight
51%
583
17%
1551
10%
582
56%
582
29%
1041
June1st to 10thNight
54%
540
19%
1440
12%
540
60%
540
38%
881
June11th to 20thNight
56%
540
22%
1440
15%
540
60%
540
39%
862
June21st to endNight
55%
540
19%
1440
13%
540
59%
540
33%
902
July1st to 10thNight
65%
525
18%
1400
15%
525
67%
525
38%
863
July11th to 20thNight
69%
522
25%
1392
17%
522
73%
522
47%
779
July21st to endNight
71%
591
28%
1487
22%
558
75%
558
45%
839
August1st to 10thNight
72%
537
23%
1554
21%
534
74%
534
41%
878
August11th to 20thNight
70%
534
21%
1776
24%
534
72%
534
33%
1007
August21st to endNight
68%
594
25%
1980
25%
594
72%
594
37%
1060
September1st to 10thNight
62%
540
26%
1800
25%
540
68%
540
34%
1015
September11th to 20thNight
66%
648
34%
1908
31%
648
69%
648
41%
1057
September21st to endNight
54%
720
29%
1980
19%
720
60%
720
37%
1201
October1st to 10thNight
52%
720
26%
1996
19%
720
57%
720
36%
1200
October11th to 20thNight
36%
720
25%
2160
14%
720
48%
720
29%
1307
October21st to endNight
26%
792
19%
2566
11%
792
36%
792
20%
1704
November1st to 10thNight
32%
740
26%
2406
17%
740
46%
740
30%
1385
November11th to 20thNight
30%
760
22%
2470
12%
760
42%
760
22%
1561
November21st to endNight
26%
760
20%
2470
12%
760
37%
760
18%
1671
December1st to 10thNight
21%
921
14%
2631
6%
921
29%
921
18%
1901
December11th to 20thNight
25%
949
15%
3192
6%
948
33%
948
16%
2250
December21st to endNight
16%
1038
7%
4856
4%
1026
23%
1026
6%
4047

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
14%9%47%6%35%5%5%7%36%
78403
Night
15%9%47%5%3445%6%38%
80943
TransparencyDay
47%5%12%21%13%2
78104
Night
47%5%11%22%14%2
80763
SeeingDay
16%8%27%26%16%7%
14660
Night
18%9%29%30%13%1
24683

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
14%13%8%14%8%3445%5%21%
2527
11th to 20thDay
14%12%6%12%10%5%5%7%7%418%
2530
21st to endDay
22%22%6%9%5%23335%18%
2942
February1st to 10thDay
16%12%5%8%7%45%446%29%
1806
11th to 20thDay
16%11%46%7%45%447%31%
1848
21st to endDay
17%13%7%8%5%33447%30%
1520
March1st to 10thDay
15%12%6%7%7%43445%32%
1800
11th to 20thDay
15%11%5%7%6%35%5%6%7%31%
1851
21st to endDay
21%13%5%8%5%35%45%6%25%
2376
April1st to 10thDay
15%9%5%7%6%246%5%7%35%
2160
11th to 20thDay
16%8%36%6%3445%7%38%
2134
21st to endDay
21%8%37%5%45%446%34%
2231
May1st to 10thDay
16%9%36%6%45%5%6%8%31%
2340
11th to 20thDay
19%7%45%6%35%45%6%36%
2340
21st to endDay
10%6%36%6%46%6%7%9%38%
2725
June1st to 10thDay
10%435%5%36%6%7%9%43%
2520
11th to 20thDay
8%5%25%5%36%5%5%9%47%
2520
21st to endDay
9%6%36%6%45%5%7%9%40%
2520
July1st to 10thDay
9%4246%35%6%7%11%43%
2520
11th to 20thDay
7%5%245%46%6%8%10%44%
2520
21st to endDay
8%5%25%5%445%7%9%46%
2743
August1st to 10thDay
6%426%5%35%5%6%9%49%
2368
11th to 20thDay
8%425%5%46%6%7%11%43%
2125
21st to endDay
7%4244345%6%9%50%
2376
September1st to 10thDay
11%5%35%6%345%6%7%44%
2160
11th to 20thDay
10%5%24435%45%7%50%
2034
21st to endDay
11%5%245%345%6%7%49%
1980
October1st to 10thDay
11%6%25%6%345%47%46%
1962
11th to 20thDay
16%7%25%5%2445%8%40%
1800
21st to endDay
19%9%46%5%245%5%7%34%
1788
November1st to 10thDay
12%6%25%3345%5%6%51%
1672
11th to 20thDay
17%9%47%5%24445%39%
1710
21st to endDay
17%9%5%8%5%34345%37%
1710
December1st to 10thDay
17%13%6%8%7%4445%5%28%
1544
11th to 20thDay
14%11%5%11%6%35%5%46%29%
1918
21st to endDay
21%19%7%12%7%35%335%14%
2783
January1st to 10thNight
16%15%7%9%5%2445%5%28%
4428
11th to 20thNight
14%18%7%11%7%45%5%4420%
4440
21st to endNight
24%16%7%8%5%2333423%
4724
February1st to 10thNight
18%11%5%8%7%45%346%29%
2371
11th to 20thNight
14%9%48%7%3445%6%35%
2218
21st to endNight
19%10%5%8%6%33446%32%
1831
March1st to 10thNight
16%11%47%6%3445%6%35%
2160
11th to 20thNight
15%9%46%5%3345%7%39%
2122
21st to endNight
19%9%47%5%35%45%6%32%
1980
April1st to 10thNight
12%8%45%5%445%5%7%41%
1800
11th to 20thNight
16%7%46%433447%41%
1775
21st to endNight
19%8%36%6%35%445%37%
1728
May1st to 10thNight
17%8%35%5%35%5%5%9%36%
1620
11th to 20thNight
16%7%25%7%3445%8%40%
1551
21st to endNight
9%6%35%7%46%5%8%8%40%
1551
June1st to 10thNight
10%43443435%8%51%
1440
11th to 20thNight
7%5%25%425%46%9%50%
1440
21st to endNight
8%5%36%6%35%5%7%9%43%
1440
July1st to 10thNight
9%4246%345%5%9%50%
1440
11th to 20thNight
5%3235%345%6%11%55%
1440
21st to endNight
5%4234345%6%8%56%
1575
August1st to 10thNight
7%4144345%7%9%52%
1563
11th to 20thNight
6%425%5%36%5%7%8%49%
1776
21st to endNight
7%3144445%5%8%55%
1980
September1st to 10thNight
13%4235%23447%53%
1800
11th to 20thNight
8%4145%2446%7%55%
1908
21st to endNight
10%5%344245%5%7%51%
1980
October1st to 10thNight
12%5%245%2445%5%53%
1996
11th to 20thNight
16%6%2442335%6%48%
2160
21st to endNight
19%8%46%5%34446%38%
2566
November1st to 10thNight
11%6%25%42445%7%50%
2406
11th to 20thNight
13%7%37%5%345%47%41%
2470
21st to endNight
18%10%47%5%24346%36%
2470
December1st to 10thNight
17%10%39%6%35%45%6%32%
2631
11th to 20thNight
16%11%5%8%6%34345%35%
3279
21st to endNight
25%17%7%10%6%3443416%
4884

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
63%5%9%15%6%
2528
11th to 20thDay
66%410%10%8%1
2530
21st to endDay
70%39%14%4
2942
February1st to 10thDay
58%411%17%9%2
1806
11th to 20thDay
53%411%22%9%1
1858
21st to endDay
56%310%21%8%2
1520
March1st to 10thDay
55%411%22%8%1
1800
11th to 20thDay
51%5%13%20%9%2
1851
21st to endDay
59%5%12%18%5%1
2376
April1st to 10thDay
48%5%13%21%14%1
2160
11th to 20thDay
46%5%12%22%12%4
2134
21st to endDay
51%5%12%19%12%2
2231
May1st to 10thDay
49%6%14%22%9%
2340
11th to 20thDay
49%6%12%18%14%1
2344
21st to endDay
42%7%13%19%16%2
2725
June1st to 10thDay
36%7%14%24%16%3
2520
11th to 20thDay
34%6%11%24%20%4
2520
21st to endDay
39%8%13%21%15%3
2520
July1st to 10thDay
33%7%15%27%14%4
2451
11th to 20thDay
32%7%16%28%14%2
2445
21st to endDay
33%7%15%26%16%2
2591
August1st to 10thDay
30%7%15%33%14%1
2353
11th to 20thDay
33%6%17%26%16%2
2125
21st to endDay
29%6%14%27%18%6%
2376
September1st to 10thDay
38%6%11%24%16%5%
2160
11th to 20thDay
33%5%12%25%21%5%
2034
21st to endDay
34%5%10%26%23%2
1980
October1st to 10thDay
38%6%10%24%19%3
1962
11th to 20thDay
42%5%11%23%18%2
1800
21st to endDay
49%5%11%22%12%1
1788
November1st to 10thDay
33%5%16%24%18%4
1672
11th to 20thDay
47%311%22%14%3
1710
21st to endDay
51%311%20%12%2
1710
December1st to 10thDay
59%5%9%19%7%
1544
11th to 20thDay
58%48%23%6%1
1915
21st to endDay
74%5%9%9%4
2783
January1st to 10thNight
58%5%11%17%8%
4428
11th to 20thNight
68%48%13%7%
4440
21st to endNight
66%38%15%7%1
4724
February1st to 10thNight
57%411%17%9%2
2371
11th to 20thNight
50%411%22%12%2
2219
21st to endNight
54%5%9%19%10%3
1831
March1st to 10thNight
50%411%21%12%1
2160
11th to 20thNight
45%412%23%14%3
2122
21st to endNight
53%5%12%20%9%1
1980
April1st to 10thNight
43%6%12%24%14%2
1800
11th to 20thNight
44%49%23%17%4
1775
21st to endNight
50%5%10%20%11%4
1728
May1st to 10thNight
46%6%12%26%11%
1620
11th to 20thNight
43%6%13%22%15%1
1552
21st to endNight
39%8%14%19%15%5%
1552
June1st to 10thNight
33%5%11%28%19%4
1440
11th to 20thNight
30%6%13%27%21%4
1440
21st to endNight
34%7%16%22%16%4
1440
July1st to 10thNight
32%6%15%27%16%4
1400
11th to 20thNight
24%6%16%31%21%3
1392
21st to endNight
25%5%15%31%19%4
1487
August1st to 10thNight
27%6%18%29%19%2
1554
11th to 20thNight
31%7%13%28%19%2
1776
21st to endNight
27%7%11%27%22%7%
1980
September1st to 10thNight
32%5%11%27%19%7%
1800
11th to 20thNight
28%49%28%26%5%
1908
21st to endNight
32%5%9%26%24%4
1980
October1st to 10thNight
33%410%26%23%3
1996
11th to 20thNight
37%48%27%21%3
2160
21st to endNight
48%39%21%16%2
2566
November1st to 10thNight
34%5%11%27%19%5%
2406
11th to 20thNight
43%411%23%16%3
2470
21st to endNight
51%39%24%13%1
2470
December1st to 10thNight
53%411%21%10%1
2631
11th to 20thNight
53%411%19%13%1
3281
21st to endNight
73%47%10%6%
4884

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
24%13%32%23%6%1
270
11th to 20thDay
27%14%37%17%41
270
21st to endDay
25%13%34%22%5%
297
February1st to 10thDay
25%14%37%20%4
270
11th to 20thDay
27%13%37%17%5%1
270
21st to endDay
27%14%44%13%2
210
March1st to 10thDay
22%18%39%19%3
240
11th to 20thDay
26%14%37%17%5%
269
21st to endDay
32%12%32%14%8%1
462
April1st to 10thDay
21%13%33%23%9%1
420
11th to 20thDay
20%15%32%19%12%2
412
21st to endDay
23%13%35%19%8%2
420
May1st to 10thDay
20%9%34%25%9%3
423
11th to 20thDay
23%6%24%29%13%5%
486
21st to endDay
12%5%30%27%17%10%
679
June1st to 10thDay
10%6%23%33%21%7%
630
11th to 20thDay
12%425%32%21%6%
630
21st to endDay
11%7%26%30%20%6%
630
July1st to 10thDay
10%215%29%26%18%
621
11th to 20thDay
8%317%34%26%13%
618
21st to endDay
10%216%32%29%11%
684
August1st to 10thDay
5%213%31%31%17%
519
11th to 20thDay
9%316%28%30%13%
439
21st to endDay
7%214%29%31%15%
495
September1st to 10thDay
13%5%16%28%29%10%
450
11th to 20thDay
10%213%29%29%16%
450
21st to endDay
12%5%25%25%22%12%
450
October1st to 10thDay
12%428%32%16%8%
432
11th to 20thDay
16%18%32%26%7%1
270
21st to endDay
30%13%34%18%41
297
November1st to 10thDay
12%11%34%23%14%4
270
11th to 20thDay
23%16%31%19%10%1
270
21st to endDay
23%10%36%27%4
270
December1st to 10thDay
19%13%41%18%7%1
270
11th to 20thDay
18%13%41%21%6%1
270
21st to endDay
25%18%37%18%4
297
January1st to 10thNight
22%13%38%24%3
950
11th to 20thNight
23%13%37%21%5%
950
21st to endNight
22%12%37%25%4
1045
February1st to 10thNight
26%11%36%24%3
851
11th to 20thNight
19%15%37%25%4
743
21st to endNight
26%12%37%21%3
611
March1st to 10thNight
21%14%35%25%5%
720
11th to 20thNight
19%12%36%26%7%
712
21st to endNight
24%8%37%25%6%1
594
April1st to 10thNight
16%13%37%29%6%
540
11th to 20thNight
20%10%33%26%10%1
533
21st to endNight
22%8%34%27%7%1
540
May1st to 10thNight
20%436%32%9%
540
11th to 20thNight
20%427%33%14%1
531
21st to endNight
11%326%38%20%2
584
June1st to 10thNight
12%322%44%19%
540
11th to 20thNight
10%325%43%19%1
540
21st to endNight
10%322%42%22%1
540
July1st to 10thNight
10%113%36%34%6%
525
11th to 20thNight
6%216%42%30%5%
522
21st to endNight
6%213%45%32%2
591
August1st to 10thNight
8%19%46%33%4
537
11th to 20thNight
7%29%45%32%4
534
21st to endNight
8%313%33%40%3
594
September1st to 10thNight
15%213%37%29%4
540
11th to 20thNight
9%314%39%31%4
648
21st to endNight
12%5%23%30%28%3
720
October1st to 10thNight
13%5%23%36%20%3
720
11th to 20thNight
19%9%31%28%13%
720
21st to endNight
23%12%35%24%6%
792
November1st to 10thNight
14%9%41%26%10%1
740
11th to 20thNight
18%13%34%28%6%1
760
21st to endNight
22%14%31%26%6%
760
December1st to 10thNight
22%12%36%25%4
921
11th to 20thNight
24%11%32%26%6%
950
21st to endNight
30%14%31%22%3
1045
Page generated at 2024-02-22 05:05:42. Version ac07

Copyright 2024 Attilla Danko


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