Enchanted Rock State Natural Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Enchanted Rock State Natural Area clear sky chart from 2005-11-05 to 2018-02-22.

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
49%
16124
28%
48898
18%
16077
59%
16077
38%
27086

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
35%
974
29%
2522
11%
970
47%
970
37%
1528
January16th to endNight
36%
929
33%
2593
13%
929
50%
929
38%
1486
February1st to 15thNight
32%
764
28%
2287
13%
758
45%
758
33%
1296
February16th to endNight
24%
660
30%
1978
7%
660
43%
660
32%
1133
March1st to 15thNight
32%
588
28%
2028
13%
588
48%
588
30%
1124
March16th to endNight
31%
576
27%
2112
16%
576
47%
576
31%
1118
April1st to 15thNight
26%
539
25%
1976
9%
539
48%
539
31%
1065
April16th to endNight
26%
540
27%
1734
12%
540
47%
540
32%
999
May1st to 15thNight
31%
539
24%
1620
14%
539
46%
539
32%
952
May16th to endNight
45%
562
24%
1685
17%
561
58%
561
36%
971
June1st to 15thNight
62%
540
23%
1620
21%
540
71%
540
54%
777
June16th to endNight
65%
540
25%
1620
25%
540
71%
540
43%
870
July1st to 15thNight
77%
510
22%
1530
23%
510
81%
510
44%
810
July16th to endNight
85%
564
28%
1594
32%
531
88%
531
50%
802
August1st to 15thNight
88%
539
30%
1709
36%
536
89%
536
54%
790
August16th to endNight
77%
573
22%
1940
27%
573
78%
573
34%
1082
September1st to 15thNight
78%
540
21%
1980
25%
540
79%
540
35%
1071
September16th to endNight
68%
537
27%
1980
26%
537
73%
537
30%
1106
October1st to 15thNight
69%
540
33%
1980
31%
540
75%
540
43%
927
October16th to endNight
55%
750
38%
2286
23%
750
65%
750
48%
1134
November1st to 15thNight
51%
830
28%
2350
15%
830
58%
830
40%
1320
November16th to endNight
47%
975
34%
2535
15%
975
57%
975
44%
1434
December1st to 15thNight
41%
975
29%
2535
13%
975
49%
975
36%
1572
December16th to endNight
35%
1040
26%
2704
10%
1040
45%
1040
32%
1719

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
9%42442445%7%50%
49344
Night
7%31332335%8%56%
49098
Cloud CoverDay
9%42442445%7%51%
49342
Night
7%31332345%8%56%
49098
TransparencyDay
33%6%10%19%20%10%
49042
Night
27%5%11%21%21%12%
48903
SeeingDay
11%6%21%34%21%5%
5878
Night
9%6%31%36%14%1
16127

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
10%6%2442333454%
1746
16th to endDay
12%312323346%56%
1992
February1st to 15thDay
12%5%14222347%54%
1900
16th to endDay
12%413323446%53%
1642
March1st to 15thDay
13%424323436%49%
1930
16th to endDay
9%424324346%52%
2112
April1st to 15thDay
9%5%25%5%23446%49%
1971
16th to endDay
10%5%35%423345%50%
2223
May1st to 15thDay
11%6%25%435%6%6%8%40%
2331
16th to endDay
12%5%35%435%6%5%7%41%
2430
June1st to 15thDay
33134345%6%9%54%
2340
16th to endDay
8%324436%5%6%10%44%
2340
July1st to 15thDay
7%3246%46%5%6%10%44%
2340
16th to endDay
6%214425%5%5%9%50%
2466
August1st to 15thDay
211332446%10%59%
2238
16th to endDay
7%316%6%5%6%6%6%9%39%
2259
September1st to 15thDay
10%426%6%245%5%8%43%
1980
16th to endDay
9%4146%35%5%5%7%45%
1980
October1st to 15thDay
8%5%13422346%56%
1980
16th to endDay
6%212112345%67%
1926
November1st to 15thDay
9%5%23423447%50%
1836
16th to endDay
9%414223225%61%
1755
December1st to 15thDay
15%5%24213346%50%
1755
16th to endDay
11%8%14424345%47%
1872
January1st to 15thNight
12%5%13313235%55%
2522
16th to endNight
11%313213347%55%
2593
February1st to 15thNight
10%6%23222345%57%
2282
16th to endNight
9%423223347%54%
1978
March1st to 15thNight
11%31442435%8%51%
2028
16th to endNight
6%32232445%8%56%
2112
April1st to 15thNight
6%323325%45%8%53%
1976
16th to endNight
7%32342445%8%53%
1734
May1st to 15thNight
7%4244235%5%7%51%
1619
16th to endNight
6%31332447%10%51%
1683
June1st to 15thNight
111131335%9%66%
1620
16th to endNight
422322446%10%57%
1620
July1st to 15thNight
321331446%10%57%
1620
16th to endNight
22222336%12%59%
1702
August1st to 15thNight
11221245%9%67%
1719
16th to endNight
5%4134345%6%10%49%
1940
September1st to 15thNight
7%2133245%7%10%50%
1980
16th to endNight
8%3134245%6%8%50%
1980
October1st to 15thNight
6%21221235%8%64%
1980
16th to endNight
6%31221333467%
2286
November1st to 15thNight
7%312323447%58%
2350
16th to endNight
7%213312336%62%
2535
December1st to 15thNight
12%5%1332435%6%51%
2535
16th to endNight
10%6%25%423345%50%
2704

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
11%6%1432333454%
1746
16th to endDay
12%323223346%56%
1992
February1st to 15thDay
12%424312347%54%
1900
16th to endDay
12%424323346%53%
1642
March1st to 15thDay
14%5%24323436%49%
1930
16th to endDay
10%424323346%53%
2110
April1st to 15thDay
9%5%25%42345%6%50%
1971
16th to endDay
11%5%25%5%23336%50%
2223
May1st to 15thDay
11%5%25%4345%6%8%41%
2331
16th to endDay
12%5%24435%5%5%7%42%
2430
June1st to 15thDay
3313325%5%5%9%55%
2340
16th to endDay
8%324435%5%6%10%45%
2340
July1st to 15thDay
8%3146%36%5%6%10%44%
2340
16th to endDay
7%314335%5%5%10%50%
2466
August1st to 15thDay
21333445%10%60%
2238
16th to endDay
7%326%7%46%7%6%9%40%
2259
September1st to 15thDay
10%425%6%245%5%8%45%
1980
16th to endDay
9%4245%25%6%6%6%46%
1980
October1st to 15thDay
8%5%23323337%57%
1980
16th to endDay
6%21221233468%
1926
November1st to 15thDay
9%5%245%23447%51%
1836
16th to endDay
9%31321323462%
1755
December1st to 15thDay
15%5%2422235%6%50%
1755
16th to endDay
11%8%2432335%5%48%
1872
January1st to 15thNight
13%5%13323235%55%
2522
16th to endNight
11%313223347%55%
2593
February1st to 15thNight
10%6%13222335%57%
2282
16th to endNight
10%413323347%55%
1978
March1st to 15thNight
11%31342435%8%51%
2028
16th to endNight
7%2222245%48%56%
2112
April1st to 15thNight
6%31333445%8%54%
1976
16th to endNight
7%22332445%9%53%
1734
May1st to 15thNight
7%41442346%7%52%
1619
16th to endNight
6%21332446%11%52%
1683
June1st to 15thNight
11122233410%66%
1620
16th to endNight
421331446%9%58%
1620
July1st to 15thNight
321332346%10%57%
1620
16th to endNight
32221336%12%61%
1702
August1st to 15thNight
11221245%9%67%
1719
16th to endNight
6%4143345%6%10%49%
1940
September1st to 15thNight
7%213225%46%11%51%
1980
16th to endNight
9%31342446%8%51%
1980
October1st to 15thNight
6%2221235%7%64%
1980
16th to endNight
5%312213335%67%
2286
November1st to 15thNight
8%313223347%59%
2350
16th to endNight
7%312322336%63%
2535
December1st to 15thNight
12%5%1331345%6%51%
2535
16th to endNight
10%6%25%323346%51%
2704

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
34%3418%26%12%
1747
16th to endDay
29%37%12%28%17%
1992
February1st to 15thDay
32%37%16%21%19%
1901
16th to endDay
32%46%19%22%15%
1642
March1st to 15thDay
36%48%13%21%14%
1930
16th to endDay
34%48%18%21%12%
2112
April1st to 15thDay
36%48%15%20%14%
1971
16th to endDay
37%46%20%19%12%
2223
May1st to 15thDay
40%7%11%12%19%8%
2331
16th to endDay
40%8%10%16%19%4
2434
June1st to 15thDay
25%7%13%23%24%6%
2340
16th to endDay
34%9%13%21%17%4
2340
July1st to 15thDay
34%8%14%26%14%2
2201
16th to endDay
26%8%20%29%13%1
2311
August1st to 15thDay
20%6%16%35%18%2
2224
16th to endDay
38%8%15%24%10%3
2259
September1st to 15thDay
38%7%10%20%17%4
1980
16th to endDay
35%8%11%17%18%8%
1980
October1st to 15thDay
30%410%20%21%12%
1980
16th to endDay
21%35%16%30%22%
1926
November1st to 15thDay
34%5%9%20%19%10%
1836
16th to endDay
28%25%17%23%22%
1755
December1st to 15thDay
37%37%17%22%11%
1755
16th to endDay
38%47%15%23%11%
1872
January1st to 15thNight
32%35%18%22%18%
2522
16th to endNight
30%35%15%25%19%
2593
February1st to 15thNight
31%36%13%22%21%
2292
16th to endNight
31%5%5%15%24%17%
1978
March1st to 15thNight
32%49%12%23%16%
2028
16th to endNight
27%6%10%19%21%13%
2112
April1st to 15thNight
29%5%9%18%18%17%
1976
16th to endNight
31%6%10%17%20%13%
1734
May1st to 15thNight
31%6%12%21%18%10%
1620
16th to endNight
28%8%15%26%17%3
1685
June1st to 15thNight
15%6%15%30%26%5%
1620
16th to endNight
23%7%15%31%18%4
1620
July1st to 15thNight
21%7%20%32%15%1
1530
16th to endNight
15%8%24%32%15%1
1594
August1st to 15thNight
13%7%18%39%19%1
1709
16th to endNight
28%8%22%26%11%3
1940
September1st to 15thNight
26%8%17%24%17%5%
1980
16th to endNight
30%8%13%19%18%9%
1980
October1st to 15thNight
20%5%15%25%20%12%
1980
16th to endNight
20%36%17%27%24%
2286
November1st to 15thNight
26%6%8%23%21%13%
2350
16th to endNight
24%47%16%23%22%
2535
December1st to 15thNight
34%48%17%22%13%
2535
16th to endNight
35%46%14%22%14%
2704

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
12%12%37%29%6%
135
16th to endDay
13%11%42%23%8%
144
February1st to 15thDay
14%16%33%28%6%
135
16th to endDay
16%16%38%26%4
100
March1st to 15thDay
17%12%44%15%10%
90
16th to endDay
410%42%34%8%
96
April1st to 15thDay
14%17%37%24%5%
90
16th to endDay
13%15%42%21%6%
333
May1st to 15thDay
16%12%39%24%6%1
468
16th to endDay
17%8%31%29%11%
517
June1st to 15thDay
4119%51%21%2
495
16th to endDay
8%114%44%26%5%
495
July1st to 15thDay
5%12%43%31%6%
475
16th to endDay
5%1441%36%10%
515
August1st to 15thDay
5%338%39%11%
393
16th to endDay
11%28%35%28%14%
299
September1st to 15thDay
5%22%51%20%
135
16th to endDay
12%130%42%12%
135
October1st to 15thDay
5%16%34%40%12%
135
16th to endDay
14%419%31%27%2
144
November1st to 15thDay
24%5%22%35%8%2
135
16th to endDay
12%13%31%26%9%6%
135
December1st to 15thDay
20%5%29%29%11%3
135
16th to endDay
23%14%31%24%6%
144
January1st to 15thNight
15%9%36%30%7%
975
16th to endNight
13%8%38%31%7%
929
February1st to 15thNight
13%12%39%29%5%
764
16th to endNight
13%13%47%23%1
660
March1st to 15thNight
13%10%40%31%3
588
16th to endNight
7%12%46%28%3
576
April1st to 15thNight
7%11%53%25%1
539
16th to endNight
7%9%53%22%6%
540
May1st to 15thNight
9%11%45%27%5%
540
16th to endNight
8%439%34%12%
563
June1st to 15thNight
130%48%18%
540
16th to endNight
3222%51%17%2
540
July1st to 15thNight
4112%54%26%1
510
16th to endNight
37%58%26%3
564
August1st to 15thNight
1449%39%4
539
16th to endNight
6%7%47%32%4
573
September1st to 15thNight
8%7%44%33%5%
540
16th to endNight
9%12%44%32%1
537
October1st to 15thNight
7%217%43%26%1
540
16th to endNight
8%429%35%19%2
750
November1st to 15thNight
10%5%30%37%15%1
830
16th to endNight
9%8%31%37%13%1
975
December1st to 15thNight
16%7%32%34%8%
975
16th to endNight
14%10%35%31%7%
1040
Page generated at 2018-02-23 10:21:40. Version ac04

Copyright 2018 A. Danko


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