County Road 2C
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the County Road 2C clear sky chart from 2005-11-05 to 2018-01-20.

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
53%
16473
27%
48460
18%
16428
61%
16428
40%
26630

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
52%
975
29%
2716
20%
970
59%
970
47%
1440
January16th to endNight
49%
879
36%
2652
22%
879
63%
879
47%
1341
February1st to 15thNight
44%
704
23%
2158
14%
700
54%
700
35%
1237
February16th to endNight
42%
632
34%
1894
17%
632
57%
632
43%
991
March1st to 15thNight
49%
720
27%
2160
18%
720
57%
720
42%
1162
March16th to endNight
42%
630
26%
2004
15%
630
54%
630
37%
1077
April1st to 15thNight
33%
539
23%
1798
10%
539
50%
539
34%
958
April16th to endNight
38%
540
21%
1795
15%
540
49%
540
28%
1057
May1st to 15thNight
45%
540
22%
1620
15%
540
54%
540
32%
980
May16th to endNight
42%
561
17%
1550
9%
561
51%
561
32%
983
June1st to 15thNight
51%
540
20%
1440
10%
540
58%
540
42%
822
June16th to endNight
60%
540
22%
1440
14%
540
65%
540
44%
827
July1st to 15thNight
68%
510
18%
1360
14%
510
70%
510
35%
853
July16th to endNight
72%
564
22%
1416
19%
531
72%
531
36%
882
August1st to 15thNight
64%
539
15%
1723
16%
536
67%
536
27%
1085
August16th to endNight
72%
573
24%
1910
28%
573
75%
573
38%
1009
September1st to 15thNight
61%
540
26%
1803
26%
540
68%
540
36%
977
September16th to endNight
64%
537
35%
1980
34%
537
73%
537
45%
895
October1st to 15thNight
50%
621
30%
2061
20%
621
59%
621
36%
1084
October16th to endNight
61%
849
38%
2385
22%
849
69%
849
53%
1183
November1st to 15thNight
60%
950
34%
2470
19%
950
66%
950
54%
1298
November16th to endNight
57%
975
37%
2535
22%
975
64%
975
54%
1332
December1st to 15thNight
50%
975
26%
2678
15%
975
57%
975
42%
1505
December16th to endNight
47%
1040
30%
2912
17%
1040
57%
1040
39%
1652

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
5%41332345%7%57%
49082
Night
5%42332345%7%56%
48632
Cloud CoverDay
5%41332345%7%57%
49080
Night
5%42432345%7%56%
48632
TransparencyDay
24%5%11%25%23%9%
48756
Night
26%5%11%25%22%8%
48460
SeeingDay
8%6%24%31%22%6%
6220
Night
7%5%28%39%17%1
16475

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
4414223235%64%
1552
16th to endDay
3413323337%64%
1687
February1st to 15thDay
35%25%423446%56%
1702
16th to endDay
25%16%31435%5%59%
1580
March1st to 15thDay
431342445%7%60%
1800
16th to endDay
7%5%2332445%7%54%
2218
April1st to 15thDay
7%42432445%7%53%
2150
16th to endDay
10%5%24425%45%7%47%
2163
May1st to 15thDay
10%41442446%8%47%
2331
16th to endDay
7%3134245%5%8%53%
2562
June1st to 15thDay
5%3123235%5%10%55%
2520
16th to endDay
21221446%9%62%
2520
July1st to 15thDay
43134246%8%10%50%
2520
16th to endDay
43134246%6%11%51%
2656
August1st to 15thDay
5%4133246%7%11%49%
2223
16th to endDay
5%31332346%9%56%
2292
September1st to 15thDay
7%31342345%6%57%
2157
16th to endDay
5%213212436%65%
1980
October1st to 15thDay
7%413212335%64%
1896
16th to endDay
4212212346%67%
1827
November1st to 15thDay
3413223346%64%
1718
16th to endDay
2312212345%69%
1755
December1st to 15thDay
46%24313346%59%
1609
16th to endDay
47%2431325%8%56%
1664
January1st to 15thNight
25%22423347%60%
2716
16th to endNight
2424312235%65%
2652
February1st to 15thNight
45%24425%447%52%
2148
16th to endNight
3424423446%59%
1894
March1st to 15thNight
45%33313446%59%
2160
16th to endNight
6%423324347%56%
2004
April1st to 15thNight
7%42322446%7%53%
1798
16th to endNight
11%6%3442435%7%47%
1795
May1st to 15thNight
10%5%1332445%7%49%
1619
16th to endNight
10%5%1432446%8%46%
1549
June1st to 15thNight
4212325%6%6%9%54%
1440
16th to endNight
33144346%6%11%52%
1440
July1st to 15thNight
5%3245%36%6%7%12%43%
1440
16th to endNight
5%423436%6%6%9%48%
1512
August1st to 15thNight
6%5%245%35%7%7%9%41%
1731
16th to endNight
6%3134245%6%10%50%
1910
September1st to 15thNight
9%3133145%7%7%51%
1803
16th to endNight
4212323346%65%
1980
October1st to 15thNight
8%413313336%58%
2061
16th to endNight
3213222335%68%
2385
November1st to 15thNight
2312223447%65%
2470
16th to endNight
2314312235%67%
2535
December1st to 15thNight
25%25%424446%56%
2678
16th to endNight
45%24423346%55%
2912

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
4423222336%63%
1552
16th to endDay
3413313337%64%
1687
February1st to 15thDay
35%25%32335%6%56%
1702
16th to endDay
25%25%32435%5%59%
1580
March1st to 15thDay
431331445%7%60%
1800
16th to endDay
7%5%2332435%7%54%
2216
April1st to 15thDay
7%4243245%5%6%53%
2150
16th to endDay
10%5%245%3445%9%46%
2163
May1st to 15thDay
9%5%2442445%8%47%
2331
16th to endDay
7%3133245%6%8%51%
2562
June1st to 15thDay
6%31232445%10%55%
2520
16th to endDay
31123135%5%9%63%
2520
July1st to 15thDay
43134245%8%9%50%
2520
16th to endDay
5%3124246%7%11%50%
2656
August1st to 15thDay
5%4134246%7%10%49%
2223
16th to endDay
5%31332445%9%56%
2292
September1st to 15thDay
7%31341345%6%57%
2157
16th to endDay
5%213213446%65%
1980
October1st to 15thDay
7%412212335%65%
1896
16th to endDay
4312212246%68%
1827
November1st to 15thDay
332331435%6%63%
1718
16th to endDay
2412112346%69%
1755
December1st to 15thDay
46%23413346%59%
1609
16th to endDay
37%23322348%57%
1664
January1st to 15thNight
25%23323347%60%
2716
16th to endNight
2424412335%65%
2652
February1st to 15thNight
45%25%325%5%47%52%
2148
16th to endNight
2424424346%60%
1894
March1st to 15thNight
5%6%22323346%59%
2160
16th to endNight
6%423324347%57%
2004
April1st to 15thNight
7%42432446%7%53%
1798
16th to endNight
12%5%25%32445%7%46%
1795
May1st to 15thNight
10%5%2332346%8%49%
1619
16th to endNight
10%5%2432445%8%47%
1549
June1st to 15thNight
432335%5%6%10%53%
1440
16th to endNight
32135%25%5%6%10%52%
1440
July1st to 15thNight
5%4145%36%5%7%11%44%
1440
16th to endNight
5%325%335%5%6%9%47%
1512
August1st to 15thNight
7%5%25%5%26%6%8%9%41%
1731
16th to endNight
6%3133336%6%10%51%
1910
September1st to 15thNight
8%313325%5%6%8%51%
1803
16th to endNight
5%213213336%65%
1980
October1st to 15thNight
8%413313346%58%
2061
16th to endNight
323322336%68%
2385
November1st to 15thNight
2412223347%66%
2470
16th to endNight
2313312235%67%
2535
December1st to 15thNight
25%25%423446%56%
2678
16th to endNight
36%24424346%56%
2912

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
23%310%30%25%6%
1553
16th to endDay
22%210%28%27%8%
1687
February1st to 15thDay
28%5%10%32%17%6%
1703
16th to endDay
27%38%26%26%8%
1580
March1st to 15thDay
21%5%10%26%25%9%
1800
16th to endDay
30%412%24%22%6%
2218
April1st to 15thDay
28%6%10%25%22%7%
2150
16th to endDay
33%5%13%22%17%6%
2163
May1st to 15thDay
33%6%11%26%17%3
2331
16th to endDay
27%6%16%24%16%7%
2566
June1st to 15thDay
21%7%14%24%19%11%
2520
16th to endDay
15%6%11%25%25%15%
2520
July1st to 15thDay
25%7%11%24%21%10%
2371
16th to endDay
24%7%14%26%21%5%
2489
August1st to 15thDay
26%8%15%25%15%9%
2207
16th to endDay
23%410%28%24%7%
2292
September1st to 15thDay
26%5%11%22%23%11%
2157
16th to endDay
19%37%23%35%10%
1980
October1st to 15thDay
23%39%22%30%10%
1896
16th to endDay
18%28%26%31%12%
1827
November1st to 15thDay
20%39%25%26%14%
1718
16th to endDay
17%28%25%32%14%
1755
December1st to 15thDay
26%310%28%25%5%
1609
16th to endDay
27%314%27%21%6%
1664
January1st to 15thNight
22%410%28%26%7%
2716
16th to endNight
23%27%30%29%7%
2652
February1st to 15thNight
30%5%11%29%17%4
2158
16th to endNight
24%39%26%26%9%
1894
March1st to 15thNight
25%410%22%28%8%
2160
16th to endNight
27%414%22%21%8%
2004
April1st to 15thNight
27%6%11%26%20%7%
1798
16th to endNight
35%5%12%22%17%5%
1795
May1st to 15thNight
32%7%13%25%16%4
1620
16th to endNight
33%7%18%18%13%8%
1550
June1st to 15thNight
23%8%20%22%15%9%
1440
16th to endNight
23%7%12%24%18%12%
1440
July1st to 15thNight
31%8%14%24%14%7%
1360
16th to endNight
31%8%15%22%18%4
1416
August1st to 15thNight
35%10%15%20%11%7%
1723
16th to endNight
25%7%14%28%18%6%
1910
September1st to 15thNight
27%6%13%22%19%10%
1803
16th to endNight
20%49%24%32%9%
1980
October1st to 15thNight
26%5%10%19%27%11%
2061
16th to endNight
18%38%24%29%15%
2385
November1st to 15thNight
18%39%24%28%15%
2470
16th to endNight
20%28%26%28%14%
2535
December1st to 15thNight
27%411%28%22%6%
2678
16th to endNight
28%412%26%23%4
2912

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%325%34%20%3
135
16th to endDay
11%6%21%38%20%2
109
February1st to 15thDay
6%5%40%35%12%
90
16th to endDay
36%45%25%12%6%
81
March1st to 15thDay
310%27%34%24%
90
16th to endDay
14%14%33%23%10%1
256
April1st to 15thDay
8%17%40%20%7%4
269
16th to endDay
15%19%31%28%5%
273
May1st to 15thDay
13%10%29%26%16%3
468
16th to endDay
11%10%27%24%21%4
517
June1st to 15thDay
7%6%25%28%23%9%
495
16th to endDay
3421%35%30%4
495
July1st to 15thDay
7%115%31%32%11%
475
16th to endDay
6%9%32%38%11%
515
August1st to 15thDay
9%18%37%26%6%
345
16th to endDay
3218%42%25%7%
332
September1st to 15thDay
5%322%37%20%10%
312
16th to endDay
14%220%22%25%14%
135
October1st to 15thDay
7%229%28%20%11%
135
16th to endDay
5%6%28%23%22%13%
144
November1st to 15thDay
5%222%40%23%5%
135
16th to endDay
10%10%24%35%19%
135
December1st to 15thDay
7%9%35%34%11%1
135
16th to endDay
5%6%33%35%17%1
144
January1st to 15thNight
5%431%39%16%2
975
16th to endNight
36%34%41%12%2
879
February1st to 15thNight
7%5%36%41%7%
704
16th to endNight
46%40%37%10%
632
March1st to 15thNight
8%5%33%38%12%2
720
16th to endNight
8%9%36%34%9%
630
April1st to 15thNight
10%9%43%30%6%
539
16th to endNight
13%13%32%28%11%
540
May1st to 15thNight
12%5%33%33%14%
540
16th to endNight
11%6%34%32%13%
563
June1st to 15thNight
5%335%40%13%1
540
16th to endNight
4325%48%17%
540
July1st to 15thNight
7%113%45%31%1
510
16th to endNight
6%110%45%34%2
564
August1st to 15thNight
8%113%44%30%1
539
16th to endNight
6%112%46%30%2
573
September1st to 15thNight
11%219%37%26%2
540
16th to endNight
6%222%41%24%2
537
October1st to 15thNight
11%6%27%34%16%3
621
16th to endNight
5%6%24%35%24%4
849
November1st to 15thNight
4427%40%20%3
950
16th to endNight
5%6%27%40%17%3
975
December1st to 15thNight
5%5%31%42%12%2
975
16th to endNight
6%8%30%39%13%1
1040
Page generated at 2018-01-21 10:19:31. Version ac04

Copyright 2018 A. Danko


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