21200 W Road And I-84
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the 21200 W Road And I-84 clear sky chart from 2005-11-06 to 2024-01-12.

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
58%
23785
21%
74496
19%
23740
62%
23740
30%
45126

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
52%
756
11%
2646
11%
756
55%
756
18%
1855
January11th to 20thNight
52%
726
14%
2391
15%
726
54%
726
19%
1672
January21st to endNight
47%
792
13%
2574
12%
792
50%
792
18%
1851
February1st to 10thNight
46%
720
12%
2340
11%
720
50%
720
18%
1645
February11th to 20thNight
53%
703
18%
2193
17%
700
57%
700
25%
1434
February21st to endNight
47%
592
19%
1776
16%
592
52%
592
24%
1196
March1st to 10thNight
52%
720
16%
2078
15%
720
54%
720
24%
1421
March11th to 20thNight
58%
720
21%
1980
17%
720
61%
720
32%
1276
March21st to endNight
50%
792
14%
2178
10%
792
53%
792
26%
1492
April1st to 10thNight
51%
720
18%
1944
11%
720
55%
720
28%
1287
April11th to 20thNight
50%
533
23%
1601
16%
533
55%
533
28%
995
April21st to endNight
53%
540
26%
1620
17%
540
59%
540
35%
953
May1st to 10thNight
53%
540
21%
1620
16%
540
56%
540
33%
950
May11th to 20thNight
61%
531
21%
1595
18%
531
62%
531
32%
952
May21st to endNight
57%
582
15%
1746
15%
582
59%
582
26%
1131
June1st to 10thNight
66%
509
21%
1455
19%
509
70%
509
42%
798
June11th to 20thNight
58%
360
27%
1260
26%
360
67%
360
38%
633
June21st to endNight
76%
360
32%
1347
41%
360
84%
360
53%
540
July1st to 10thNight
74%
350
24%
1400
33%
350
78%
350
43%
606
July11th to 20thNight
71%
428
27%
1472
31%
428
74%
428
49%
661
July21st to endNight
76%
591
28%
1674
27%
558
78%
558
50%
837
August1st to 10thNight
75%
537
29%
1602
24%
534
77%
534
45%
830
August11th to 20thNight
76%
534
33%
1602
25%
534
78%
534
50%
798
August21st to endNight
74%
594
38%
1782
32%
594
77%
594
51%
874
September1st to 10thNight
76%
692
32%
1923
25%
692
80%
692
56%
956
September11th to 20thNight
76%
720
35%
1980
30%
720
78%
720
56%
1006
September21st to endNight
71%
720
36%
1980
28%
720
75%
720
53%
1022
October1st to 10thNight
67%
720
28%
2043
22%
720
71%
720
44%
1113
October11th to 20thNight
66%
720
32%
2160
26%
720
71%
720
42%
1159
October21st to endNight
63%
792
30%
2455
25%
792
70%
792
40%
1316
November1st to 10thNight
62%
740
24%
2405
24%
740
65%
740
30%
1427
November11th to 20thNight
58%
760
22%
2470
21%
760
62%
760
30%
1467
November21st to endNight
57%
890
20%
2600
16%
890
60%
890
31%
1617
December1st to 10thNight
48%
950
13%
2660
9%
950
51%
950
22%
1884
December11th to 20thNight
45%
948
12%
3178
8%
948
48%
948
15%
2381
December21st to endNight
36%
903
7%
4766
8%
897
40%
897
9%
3091

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
7%7%35%5%3445%7%49%
74823
Night
8%8%36%5%3445%7%47%
74860
TransparencyDay
33%6%12%20%18%11%
74536
Night
36%6%12%20%17%9%
74667
SeeingDay
9%6%19%32%25%9%
13868
Night
11%416%39%25%4
23807

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 10thDay
12%14%5%9%8%5%5%35%6%27%
1519
11th to 20thDay
10%13%48%7%5%6%5%6%7%29%
1590
21st to endDay
12%15%6%11%10%5%4446%21%
1782
February1st to 10thDay
11%14%6%9%6%3346%8%31%
1620
11th to 20thDay
11%12%48%6%345%5%7%34%
1650
21st to endDay
7%12%6%8%6%46%6%6%7%33%
1480
March1st to 10thDay
9%11%46%5%45%5%6%8%39%
1881
11th to 20thDay
7%9%47%5%35%6%7%10%37%
1980
21st to endDay
10%13%48%6%445%5%8%32%
2178
April1st to 10thDay
10%9%46%5%35%45%6%41%
2011
11th to 20thDay
8%9%36%6%445%6%8%42%
2307
21st to endDay
8%7%35%6%35%5%6%8%45%
2340
May1st to 10thDay
7%7%25%6%35%5%6%8%47%
2340
11th to 20thDay
7%425%7%36%5%7%10%45%
2301
21st to endDay
8%6%36%6%45%6%6%7%42%
2530
June1st to 10thDay
5%424435%5%6%9%54%
2492
11th to 20thDay
6%42442445%8%58%
2700
21st to endDay
2212222446%72%
2605
July1st to 10thDay
22123235%6%8%65%
2520
11th to 20thDay
331331335%5%69%
2435
21st to endDay
43123245%6%7%63%
2545
August1st to 10thDay
5%31442345%7%62%
2328
11th to 20thDay
421232345%8%68%
2299
21st to endDay
5%32332335%6%66%
2574
September1st to 10thDay
431342335%469%
2031
11th to 20thDay
43134235%46%65%
1980
21st to endDay
7%313312435%67%
1980
October1st to 10thDay
10%42443435%6%54%
1916
11th to 20thDay
7%5%244335%5%7%55%
1800
21st to endDay
6%5%25%5%3445%7%55%
1900
November1st to 10thDay
11%9%45%5%3445%6%43%
1674
11th to 20thDay
12%7%243245%5%8%49%
1710
21st to endDay
8%11%5%7%6%43447%42%
1558
December1st to 10thDay
11%13%5%8%7%35%445%35%
1520
11th to 20thDay
13%12%49%9%5%6%6%6%7%24%
1926
21st to endDay
9%11%6%10%7%346%6%6%32%
2821
January1st to 10thNight
12%13%47%5%3446%8%34%
2646
11th to 20thNight
11%13%47%6%35%5%5%9%33%
2391
21st to endNight
11%14%5%8%6%35%45%8%32%
2574
February1st to 10thNight
10%14%5%8%5%345%6%6%35%
2340
11th to 20thNight
10%10%46%5%2445%6%43%
2192
21st to endNight
7%12%5%8%6%345%6%6%37%
1776
March1st to 10thNight
8%12%46%6%35%5%6%8%35%
2078
11th to 20thNight
7%7%36%6%35%6%6%9%43%
1980
21st to endNight
9%9%5%7%6%35%6%6%7%38%
2178
April1st to 10thNight
9%9%37%5%245%46%44%
1944
11th to 20thNight
9%7%47%5%35%446%46%
1601
21st to endNight
9%6%245%345%5%7%50%
1620
May1st to 10thNight
7%6%35%6%3446%7%49%
1620
11th to 20thNight
8%6%35%6%25%47%9%45%
1594
21st to endNight
11%6%36%5%45%5%6%7%42%
1746
June1st to 10thNight
6%324335%5%6%6%56%
1455
11th to 20thNight
7%42442436%7%57%
1260
21st to endNight
2312323445%72%
1347
July1st to 10thNight
3223435%45%8%62%
1440
11th to 20thNight
441332445%6%65%
1520
21st to endNight
2314435%5%6%8%60%
1773
August1st to 10thNight
44245%35%6%6%8%56%
1611
11th to 20thNight
3414424446%63%
1602
21st to endNight
5%31332445%6%65%
1782
September1st to 10thNight
3214324435%70%
1923
11th to 20thNight
6%21222245%5%68%
1980
21st to endNight
6%413313335%68%
1980
October1st to 10thNight
8%5%2442445%6%59%
2043
11th to 20thNight
9%5%23323346%60%
2160
21st to endNight
6%4245%2445%7%57%
2455
November1st to 10thNight
11%8%245%3445%8%48%
2405
11th to 20thNight
9%7%35%5%245%5%7%49%
2470
21st to endNight
7%9%36%6%345%5%7%46%
2600
December1st to 10thNight
10%10%49%6%3445%7%37%
2660
11th to 20thNight
12%11%5%8%6%5%5%5%5%8%29%
3271
21st to endNight
9%11%5%9%8%45%5%5%6%33%
4843

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
58%10%15%14%31
1519
11th to 20thDay
54%9%14%17%41
1590
21st to endDay
65%7%12%11%41
1782
February1st to 10thDay
52%9%15%17%6%1
1620
11th to 20thDay
48%8%14%21%7%2
1659
21st to endDay
49%7%15%19%9%1
1480
March1st to 10thDay
42%8%15%24%9%2
1881
11th to 20thDay
40%8%16%25%11%1
1980
21st to endDay
49%7%17%20%7%1
2178
April1st to 10thDay
42%7%13%22%12%4
2011
11th to 20thDay
38%6%11%25%17%2
2310
21st to endDay
35%6%12%27%19%1
2340
May1st to 10thDay
32%6%10%27%22%3
2340
11th to 20thDay
31%7%11%29%15%6%
2304
21st to endDay
38%7%12%24%16%3
2530
June1st to 10thDay
25%6%11%26%27%4
2492
11th to 20thDay
24%411%18%26%16%
2700
21st to endDay
14%26%14%34%31%
2605
July1st to 10thDay
15%37%16%25%33%
2451
11th to 20thDay
17%26%12%27%37%
2360
21st to endDay
18%47%11%26%33%
2404
August1st to 10thDay
20%48%16%24%29%
2313
11th to 20thDay
15%37%14%34%27%
2299
21st to endDay
19%26%16%32%24%
2574
September1st to 10thDay
18%46%15%28%29%
2031
11th to 20thDay
19%5%8%21%28%21%
1980
21st to endDay
20%29%22%37%10%
1980
October1st to 10thDay
31%5%11%24%23%6%
1916
11th to 20thDay
26%6%13%31%20%3
1800
21st to endDay
27%6%18%31%17%1
1900
November1st to 10thDay
41%6%15%22%15%1
1674
11th to 20thDay
33%7%22%28%10%1
1710
21st to endDay
43%5%18%24%11%1
1558
December1st to 10thDay
52%9%14%16%8%2
1520
11th to 20thDay
57%11%17%13%3
1924
21st to endDay
51%7%16%16%9%1
2821
January1st to 10thNight
47%10%19%18%5%1
2646
11th to 20thNight
48%8%17%20%5%1
2391
21st to endNight
51%7%17%15%7%2
2574
February1st to 10thNight
49%8%16%22%5%
2340
11th to 20thNight
42%6%14%22%14%2
2193
21st to endNight
46%5%13%23%11%2
1776
March1st to 10thNight
45%7%14%24%9%1
2078
11th to 20thNight
38%6%14%24%16%2
1980
21st to endNight
44%6%16%22%10%2
2178
April1st to 10thNight
41%5%13%22%13%7%
1944
11th to 20thNight
39%5%11%23%20%3
1601
21st to endNight
33%5%11%25%22%3
1620
May1st to 10thNight
33%5%10%23%24%4
1620
11th to 20thNight
34%6%10%25%18%8%
1595
21st to endNight
39%8%11%22%19%2
1746
June1st to 10thNight
25%6%12%24%27%7%
1455
11th to 20thNight
26%49%17%28%16%
1260
21st to endNight
15%3413%30%35%
1347
July1st to 10thNight
19%5%7%13%25%30%
1400
11th to 20thNight
20%36%10%25%35%
1472
21st to endNight
20%47%11%22%35%
1674
August1st to 10thNight
24%48%15%20%28%
1602
11th to 20thNight
22%26%11%29%30%
1602
21st to endNight
20%36%12%30%29%
1782
September1st to 10thNight
18%36%14%23%36%
1923
11th to 20thNight
17%47%16%31%25%
1980
21st to endNight
21%36%18%34%18%
1980
October1st to 10thNight
26%411%21%31%8%
2043
11th to 20thNight
27%47%31%25%7%
2160
21st to endNight
26%5%12%32%21%3
2455
November1st to 10thNight
36%5%14%24%18%3
2405
11th to 20thNight
34%7%15%29%14%1
2470
21st to endNight
36%6%15%30%11%2
2600
December1st to 10thNight
47%7%17%19%7%3
2660
11th to 20thNight
53%9%15%18%5%
3272
21st to endNight
51%6%17%15%10%
4843

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
14%7%19%29%18%12%
180
11th to 20thDay
16%419%31%20%10%
226
21st to endDay
17%5%18%33%20%7%
264
February1st to 10thDay
23%7%15%36%13%7%
240
11th to 20thDay
16%6%21%37%15%5%
315
21st to endDay
11%6%25%38%18%3
346
March1st to 10thDay
15%5%16%39%21%4
420
11th to 20thDay
10%5%17%35%26%7%
420
21st to endDay
15%8%25%33%18%2
462
April1st to 10thDay
17%8%22%30%20%4
420
11th to 20thDay
10%14%28%30%13%6%
412
21st to endDay
11%14%26%25%17%7%
420
May1st to 10thDay
7%11%26%29%24%4
423
11th to 20thDay
12%7%21%29%24%7%
448
21st to endDay
8%8%19%28%26%11%
485
June1st to 10thDay
6%6%19%28%30%11%
576
11th to 20thDay
8%6%23%33%25%5%
630
21st to endDay
3423%38%24%9%
535
July1st to 10thDay
3417%35%31%10%
446
11th to 20thDay
5%222%34%30%7%
444
21st to endDay
5%112%31%37%14%
487
August1st to 10thDay
7%215%32%33%11%
447
11th to 20thDay
4311%31%36%16%
437
21st to endDay
4413%28%34%18%
495
September1st to 10thDay
35%14%26%32%20%
450
11th to 20thDay
5%314%34%29%14%
450
21st to endDay
8%418%22%37%11%
450
October1st to 10thDay
10%5%19%28%25%14%
386
11th to 20thDay
8%7%23%23%24%15%
270
21st to endDay
7%10%23%36%20%4
297
November1st to 10thDay
16%9%19%33%16%7%
270
11th to 20thDay
10%8%19%40%15%9%
270
21st to endDay
14%5%19%31%24%7%
270
December1st to 10thDay
15%5%21%34%18%7%
270
11th to 20thDay
14%5%15%40%23%3
270
21st to endDay
16%9%16%35%16%7%
237
January1st to 10thNight
17%415%36%23%5%
760
11th to 20thNight
17%316%35%25%5%
726
21st to endNight
18%415%35%23%5%
792
February1st to 10thNight
17%321%39%18%2
720
11th to 20thNight
16%218%41%20%2
704
21st to endNight
11%5%22%40%20%3
592
March1st to 10thNight
15%6%15%44%17%3
720
11th to 20thNight
10%319%42%24%3
720
21st to endNight
13%6%20%41%18%2
792
April1st to 10thNight
13%8%18%40%18%3
720
11th to 20thNight
12%6%21%42%16%3
533
21st to endNight
11%6%22%34%23%3
540
May1st to 10thNight
9%6%24%40%20%3
540
11th to 20thNight
11%5%15%35%29%4
531
21st to endNight
12%6%15%32%30%5%
584
June1st to 10thNight
6%6%16%36%33%3
509
11th to 20thNight
9%6%21%38%25%1
360
21st to endNight
3315%43%32%4
360
July1st to 10thNight
2215%37%40%4
350
11th to 20thNight
4217%47%30%1
428
21st to endNight
3110%42%40%4
591
August1st to 10thNight
5%110%47%34%3
537
11th to 20thNight
4210%43%38%2
534
21st to endNight
6%312%38%36%5%
594
September1st to 10thNight
5%211%39%35%9%
692
11th to 20thNight
6%211%36%36%9%
720
21st to endNight
8%314%35%31%10%
720
October1st to 10thNight
9%314%38%30%5%
720
11th to 20thNight
11%5%12%36%31%5%
720
21st to endNight
8%418%39%27%4
792
November1st to 10thNight
13%5%12%39%26%4
740
11th to 20thNight
13%217%43%20%4
760
21st to endNight
9%5%18%40%24%4
890
December1st to 10thNight
15%5%16%42%21%1
950
11th to 20thNight
19%418%39%18%2
950
21st to endNight
20%6%20%38%14%2
916
Page generated at 2024-01-09 05:14:41. Version ac07

Copyright 2024 Attilla Danko


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