McCurdy Road
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the McCurdy Road 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
55%
16469
27%
48478
19%
16426
62%
16426
40%
26641

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
53%
974
29%
2716
21%
970
61%
970
48%
1436
January16th to endNight
54%
850
36%
2623
25%
850
66%
850
47%
1308
February1st to 15thNight
44%
703
24%
2187
14%
700
55%
700
36%
1217
February16th to endNight
44%
632
34%
1894
18%
632
59%
632
43%
987
March1st to 15thNight
50%
720
28%
2157
17%
720
59%
720
43%
1156
March16th to endNight
45%
650
27%
1994
16%
650
57%
650
40%
1062
April1st to 15thNight
36%
539
24%
1798
13%
539
52%
539
35%
957
April16th to endNight
40%
540
22%
1800
16%
540
52%
540
28%
1054
May1st to 15thNight
47%
540
21%
1644
16%
540
55%
540
31%
995
May16th to endNight
47%
561
18%
1520
9%
561
55%
561
33%
956
June1st to 15thNight
55%
540
20%
1440
13%
540
60%
540
42%
816
June16th to endNight
64%
540
22%
1440
16%
540
68%
540
44%
822
July1st to 15thNight
67%
510
16%
1360
13%
510
68%
510
31%
886
July16th to endNight
73%
564
21%
1422
19%
531
73%
531
35%
881
August1st to 15thNight
66%
539
14%
1728
16%
536
67%
536
25%
1085
August16th to endNight
75%
573
24%
1910
28%
573
76%
573
35%
1048
September1st to 15thNight
65%
540
26%
1800
25%
540
71%
540
35%
985
September16th to endNight
67%
537
34%
1964
33%
537
74%
537
44%
899
October1st to 15thNight
51%
654
29%
2094
19%
654
60%
654
37%
1120
October16th to endNight
62%
823
38%
2359
23%
823
70%
823
52%
1171
November1st to 15thNight
60%
950
34%
2470
19%
950
65%
950
54%
1307
November16th to endNight
58%
975
37%
2535
22%
975
65%
975
54%
1316
December1st to 15thNight
52%
975
25%
2711
16%
975
58%
975
40%
1542
December16th to endNight
48%
1040
30%
2912
17%
1040
58%
1040
41%
1635

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%41332445%8%55%
49064
Night
5%42332445%7%56%
48651
Cloud CoverDay
5%41332445%8%55%
49062
Night
5%42332345%7%56%
48651
TransparencyDay
25%5%11%24%23%9%
48739
Night
26%5%11%24%22%9%
48478
SeeingDay
8%6%26%30%21%7%
6205
Night
6%427%38%19%2
16473

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
3423323247%63%
1552
16th to endDay
35%23322247%63%
1716
February1st to 15thDay
26%35%423447%56%
1674
16th to endDay
16%24423346%58%
1580
March1st to 15thDay
442342345%6%58%
1800
16th to endDay
6%6%23423448%52%
2229
April1st to 15thDay
6%414325%45%7%54%
2150
16th to endDay
10%5%1442446%8%47%
2160
May1st to 15thDay
9%6%33435%46%8%44%
2307
16th to endDay
7%4133245%7%9%50%
2593
June1st to 15thDay
6%21232447%11%52%
2520
16th to endDay
22123245%6%9%58%
2520
July1st to 15thDay
6%313425%6%7%10%47%
2520
16th to endDay
5%313425%6%9%10%46%
2648
August1st to 15thDay
5%324425%6%8%11%45%
2220
16th to endDay
6%3143235%6%9%53%
2292
September1st to 15thDay
6%31342446%8%54%
2160
16th to endDay
5%212213336%66%
1995
October1st to 15thDay
6%312322336%63%
1864
16th to endDay
4312113236%68%
1851
November1st to 15thDay
2313324347%62%
1718
16th to endDay
231321125%6%68%
1755
December1st to 15thDay
26%14333337%58%
1576
16th to endDay
37%2431335%7%56%
1664
January1st to 15thNight
2424312346%62%
2716
16th to endNight
2423313345%65%
2623
February1st to 15thNight
45%245%2445%7%54%
2177
16th to endNight
25%23313346%61%
1894
March1st to 15thNight
35%24324346%59%
2157
16th to endNight
6%41322445%7%57%
1994
April1st to 15thNight
6%5%23433447%55%
1798
16th to endNight
11%6%24424347%48%
1800
May1st to 15thNight
10%5%2332447%8%46%
1643
16th to endNight
8%6%23325%5%6%8%47%
1519
June1st to 15thNight
4212325%5%6%10%54%
1440
16th to endNight
34133146%7%10%53%
1440
July1st to 15thNight
7%3145%36%7%7%9%42%
1440
16th to endNight
5%3245%25%6%8%10%45%
1518
August1st to 15thNight
7%425%5%45%5%8%7%42%
1737
16th to endNight
6%3134346%7%10%47%
1910
September1st to 15thNight
7%3144245%6%8%51%
1800
16th to endNight
5%313223447%62%
1964
October1st to 15thNight
8%5%13323345%58%
2094
16th to endNight
4312213346%67%
2359
November1st to 15thNight
2313214347%64%
2470
16th to endNight
3312312336%67%
2535
December1st to 15thNight
15%25%423447%56%
2711
16th to endNight
36%2332445%6%57%
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
3423322247%62%
1552
16th to endDay
35%23312246%63%
1716
February1st to 15thDay
26%35%423346%56%
1674
16th to endDay
17%25%323346%58%
1580
March1st to 15thDay
45%2331435%6%59%
1800
16th to endDay
6%7%2441345%7%52%
2227
April1st to 15thDay
7%41333445%6%54%
2150
16th to endDay
10%5%245%2435%8%48%
2160
May1st to 15thDay
10%5%25%435%5%6%7%44%
2307
16th to endDay
8%3133245%6%10%50%
2593
June1st to 15thDay
6%312225%5%7%10%53%
2520
16th to endDay
311232446%9%59%
2520
July1st to 15thDay
6%314425%5%8%10%47%
2520
16th to endDay
6%213425%7%8%10%47%
2648
August1st to 15thDay
6%314425%6%9%10%46%
2220
16th to endDay
6%3134135%6%9%53%
2292
September1st to 15thDay
6%31332446%7%54%
2160
16th to endDay
5%22222346%66%
1995
October1st to 15thDay
6%312212346%63%
1864
16th to endDay
4312212236%68%
1851
November1st to 15thDay
231332445%6%62%
1718
16th to endDay
13132225%6%69%
1755
December1st to 15thDay
36%13324337%59%
1576
16th to endDay
36%34312446%57%
1664
January1st to 15thNight
25%24313347%62%
2716
16th to endNight
2424313335%65%
2623
February1st to 15thNight
46%2442345%6%55%
2177
16th to endNight
2424314345%62%
1894
March1st to 15thNight
35%23423346%59%
2157
16th to endNight
6%413223447%58%
1994
April1st to 15thNight
6%5%1341345%7%55%
1798
16th to endNight
12%6%13433447%48%
1800
May1st to 15thNight
11%4243245%6%7%48%
1643
16th to endNight
9%5%23325%5%5%8%48%
1519
June1st to 15thNight
4212425%5%6%10%54%
1440
16th to endNight
24133245%6%10%54%
1440
July1st to 15thNight
7%3235%36%7%7%9%43%
1440
16th to endNight
5%325%5%25%6%8%10%45%
1518
August1st to 15thNight
7%5%25%5%35%6%6%8%43%
1737
16th to endNight
7%314325%5%7%11%47%
1910
September1st to 15thNight
8%3134145%6%8%51%
1800
16th to endNight
5%31231335%7%62%
1964
October1st to 15thNight
8%413423345%58%
2094
16th to endNight
433213346%67%
2359
November1st to 15thNight
2323223347%64%
2470
16th to endNight
2312312346%67%
2535
December1st to 15thNight
15%25%423346%57%
2711
16th to endNight
35%23324447%57%
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
22%39%30%27%6%
1553
16th to endDay
22%28%29%27%9%
1716
February1st to 15thDay
28%411%30%18%6%
1675
16th to endDay
27%36%26%26%9%
1580
March1st to 15thDay
24%5%10%25%24%10%
1800
16th to endDay
29%411%23%23%6%
2229
April1st to 15thDay
28%5%10%24%21%8%
2150
16th to endDay
31%6%13%24%18%6%
2160
May1st to 15thDay
34%6%12%22%18%4
2307
16th to endDay
26%7%17%24%16%7%
2597
June1st to 15thDay
23%6%15%23%19%12%
2520
16th to endDay
17%5%10%23%27%14%
2520
July1st to 15thDay
27%7%13%22%18%11%
2371
16th to endDay
26%8%14%25%19%4
2481
August1st to 15thDay
27%10%15%22%14%10%
2205
16th to endDay
24%5%11%27%23%6%
2292
September1st to 15thDay
26%5%11%24%22%10%
2160
16th to endDay
18%47%22%34%12%
1995
October1st to 15thDay
21%310%19%32%11%
1864
16th to endDay
18%28%25%31%14%
1851
November1st to 15thDay
20%29%25%27%14%
1718
16th to endDay
16%27%25%32%15%
1755
December1st to 15thDay
26%311%28%22%7%
1576
16th to endDay
27%312%28%21%7%
1664
January1st to 15thNight
22%310%29%26%7%
2716
16th to endNight
21%38%28%28%8%
2623
February1st to 15thNight
28%5%11%29%19%4
2187
16th to endNight
22%48%28%25%10%
1894
March1st to 15thNight
25%39%24%28%7%
2157
16th to endNight
25%414%22%25%7%
1994
April1st to 15thNight
27%5%11%26%20%9%
1798
16th to endNight
35%412%23%17%6%
1800
May1st to 15thNight
33%7%14%22%15%5%
1644
16th to endNight
33%8%16%19%13%9%
1520
June1st to 15thNight
22%8%19%21%15%12%
1440
16th to endNight
24%7%13%21%18%14%
1440
July1st to 15thNight
35%9%12%21%13%7%
1360
16th to endNight
30%9%16%23%17%3
1422
August1st to 15thNight
36%9%14%20%10%7%
1728
16th to endNight
27%7%13%25%18%6%
1910
September1st to 15thNight
28%6%14%22%19%9%
1800
16th to endNight
20%49%24%30%10%
1964
October1st to 15thNight
26%5%9%18%29%10%
2094
16th to endNight
18%38%25%28%15%
2359
November1st to 15thNight
19%39%24%27%16%
2470
16th to endNight
19%28%25%30%13%
2535
December1st to 15thNight
27%5%11%27%21%7%
2711
16th to endNight
27%413%24%25%5%
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%5%22%34%20%4
135
16th to endDay
7%7%21%44%16%2
109
February1st to 15thDay
8%247%31%10%
90
16th to endDay
47%44%28%11%3
81
March1st to 15thDay
37%30%41%16%1
90
16th to endDay
11%18%37%22%6%3
288
April1st to 15thDay
9%16%40%21%8%3
269
16th to endDay
18%18%35%20%7%
270
May1st to 15thDay
13%9%32%25%14%4
444
16th to endDay
12%8%29%24%17%6%
517
June1st to 15thDay
7%5%27%27%23%9%
495
16th to endDay
4320%33%29%9%
495
July1st to 15thDay
7%115%30%33%10%
475
16th to endDay
6%10%29%38%14%
507
August1st to 15thDay
6%221%35%25%8%
315
16th to endDay
5%215%37%30%9%
332
September1st to 15thDay
5%129%34%19%10%
315
16th to endDay
14%126%23%22%12%
150
October1st to 15thDay
8%425%30%21%9%
135
16th to endDay
6%5%24%26%31%6%
144
November1st to 15thDay
1330%35%25%3
135
16th to endDay
6%11%27%37%16%
135
December1st to 15thDay
411%37%34%11%
135
16th to endDay
7%5%25%45%15%
144
January1st to 15thNight
4431%38%16%3
975
16th to endNight
4431%42%14%3
850
February1st to 15thNight
6%440%38%9%
704
16th to endNight
47%39%36%9%1
632
March1st to 15thNight
45%35%37%14%2
720
16th to endNight
7%7%37%36%11%
650
April1st to 15thNight
8%10%42%31%7%
539
16th to endNight
14%10%29%32%12%
540
May1st to 15thNight
11%7%30%33%15%1
540
16th to endNight
12%5%31%32%17%1
563
June1st to 15thNight
5%429%42%16%1
540
16th to endNight
4220%45%25%
540
July1st to 15thNight
8%14%39%33%3
510
16th to endNight
6%6%39%41%4
564
August1st to 15thNight
8%110%41%35%2
539
16th to endNight
7%8%41%36%4
573
September1st to 15thNight
8%117%37%29%5%
540
16th to endNight
7%219%41%26%2
537
October1st to 15thNight
10%6%26%32%18%5%
654
16th to endNight
5%424%33%27%4
823
November1st to 15thNight
4326%39%23%3
950
16th to endNight
6%5%25%42%17%3
975
December1st to 15thNight
46%29%43%14%1
975
16th to endNight
7%6%30%39%13%2
1040
Page generated at 2018-01-21 10:19:22. Version ac04

Copyright 2018 A. Danko


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