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 2017-09-17.

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%
15901
27%
46860
19%
15858
62%
15858
40%
25819

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%
899
30%
2506
21%
895
61%
895
47%
1332
January16th to endNight
52%
825
35%
2553
24%
825
64%
825
46%
1282
February1st to 15thNight
45%
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
49%
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
41%
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
66%
510
16%
1360
13%
510
68%
510
31%
886
July16th to endNight
73%
564
21%
1422
19%
531
72%
531
35%
881
August1st to 15thNight
67%
539
14%
1728
16%
536
68%
536
25%
1085
August16th to endNight
76%
573
24%
1910
28%
573
77%
573
35%
1048
September1st to 15thNight
66%
540
26%
1800
25%
540
72%
540
35%
985
September16th to endNight
70%
498
34%
1821
34%
498
76%
498
47%
799
October1st to 15thNight
52%
599
30%
1919
20%
599
60%
599
37%
1029
October16th to endNight
63%
754
36%
2162
22%
754
70%
754
52%
1074
November1st to 15thNight
62%
875
35%
2275
20%
875
67%
875
56%
1192
November16th to endNight
58%
900
36%
2340
22%
900
65%
900
54%
1229
December1st to 15thNight
52%
900
25%
2502
15%
900
58%
900
38%
1450
December16th to endNight
47%
960
29%
2688
16%
960
57%
960
40%
1525

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%
47930
Night
5%42332445%7%56%
47033
Cloud CoverDay
5%41332445%8%55%
47928
Night
5%42332445%7%56%
47033
TransparencyDay
25%5%11%25%23%9%
47605
Night
26%5%11%24%22%8%
46860
SeeingDay
8%6%26%29%22%7%
5829
Night
7%427%38%19%2
15905

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
3433323247%63%
1432
16th to endDay
35%23322347%62%
1682
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
322213336%69%
1843
October1st to 15thDay
5%412322346%62%
1709
16th to endDay
4312213236%68%
1697
November1st to 15thDay
2313324347%62%
1583
16th to endDay
231321125%6%68%
1620
December1st to 15thDay
36%14433337%56%
1455
16th to endDay
47%2431335%7%55%
1536
January1st to 15thNight
2424312346%61%
2506
16th to endNight
2423313345%64%
2553
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
411322345%7%64%
1821
October1st to 15thNight
7%5%13323346%58%
1919
16th to endNight
3312213246%67%
2162
November1st to 15thNight
2213214347%65%
2275
16th to endNight
3412312336%66%
2340
December1st to 15thNight
25%36%434447%54%
2502
16th to endNight
36%23324446%57%
2688

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
3422322247%62%
1432
16th to endDay
35%23312347%63%
1682
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
322222346%69%
1843
October1st to 15thDay
6%413212346%63%
1709
16th to endDay
5%312212235%68%
1697
November1st to 15thDay
321332435%6%62%
1583
16th to endDay
13132225%6%68%
1620
December1st to 15thDay
36%23334337%57%
1455
16th to endDay
47%34313446%55%
1536
January1st to 15thNight
25%24313347%61%
2506
16th to endNight
2424313335%64%
2553
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
321231335%7%64%
1821
October1st to 15thNight
8%413413346%58%
1919
16th to endNight
333213247%67%
2162
November1st to 15thNight
2212224346%66%
2275
16th to endNight
2413322335%67%
2340
December1st to 15thNight
25%26%5%2345%6%55%
2502
16th to endNight
36%33424447%56%
2688

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%
1433
16th to endDay
22%28%29%25%9%
1682
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
15%48%23%35%13%
1843
October1st to 15thDay
22%310%20%32%10%
1709
16th to endDay
18%27%25%32%13%
1697
November1st to 15thDay
20%29%24%26%15%
1583
16th to endDay
16%27%26%31%16%
1620
December1st to 15thDay
27%312%28%21%5%
1455
16th to endDay
28%312%28%19%7%
1536
January1st to 15thNight
22%310%29%26%7%
2506
16th to endNight
22%38%28%27%9%
2553
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
18%410%25%30%10%
1821
October1st to 15thNight
26%6%9%18%30%9%
1919
16th to endNight
18%48%25%28%14%
2162
November1st to 15thNight
18%39%24%26%17%
2275
16th to endNight
20%27%24%30%13%
2340
December1st to 15thNight
29%5%11%27%20%5%
2502
16th to endNight
28%412%24%24%5%
2688

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
16%5%17%28%25%5%
90
16th to endDay
8%8%23%44%13%1
96
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
5%27%23%25%16%
108
October1st to 15thDay
6%421%32%23%12%
90
16th to endDay
7%323%23%33%8%
96
November1st to 15thDay
1326%28%34%5%
90
16th to endDay
10%10%30%35%13%1
90
December1st to 15thDay
5%7%46%30%10%
90
16th to endDay
10%5%20%50%13%
96
January1st to 15thNight
4431%37%17%4
900
16th to endNight
4431%42%13%3
825
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
5%217%43%28%3
498
October1st to 15thNight
10%5%26%31%18%6%
599
16th to endNight
5%5%23%34%26%5%
754
November1st to 15thNight
4326%38%23%3
875
16th to endNight
6%5%26%41%17%3
900
December1st to 15thNight
46%29%43%13%2
900
16th to endNight
7%6%30%38%13%2
960
Page generated at 2017-09-18 06:38:19. Version ac04

Copyright 2017 A. Danko


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