Kellogg
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Kellogg clear sky chart from 2005-11-05 to 2017-09-16.

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
36%
16094
16%
46855
9%
16048
43%
16048
23%
31424

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
27%
900
12%
2506
5%
895
33%
895
17%
1849
January16th to endNight
22%
960
12%
2574
4%
960
28%
960
16%
1981
February1st to 15thNight
26%
879
14%
2288
4%
875
33%
875
20%
1650
February16th to endNight
27%
711
17%
1973
6%
711
35%
711
21%
1365
March1st to 15thNight
31%
622
15%
2062
9%
622
37%
622
21%
1355
March16th to endNight
35%
576
16%
2067
14%
576
42%
576
18%
1408
April1st to 15thNight
30%
539
15%
1797
10%
539
40%
539
20%
1195
April16th to endNight
30%
540
16%
1732
11%
540
39%
540
19%
1195
May1st to 15thNight
33%
540
15%
1464
9%
540
38%
540
24%
1014
May16th to endNight
43%
562
16%
1497
6%
561
49%
561
29%
991
June1st to 15thNight
49%
540
13%
1440
5%
540
52%
540
31%
938
June16th to endNight
54%
540
16%
1440
6%
540
58%
540
39%
870
July1st to 15thNight
61%
510
17%
1360
8%
510
63%
510
46%
763
July16th to endNight
68%
564
22%
1417
13%
531
71%
531
46%
796
August1st to 15thNight
65%
539
22%
1593
19%
536
68%
536
36%
928
August16th to endNight
55%
573
21%
1836
20%
573
61%
573
34%
1043
September1st to 15thNight
57%
540
23%
1800
22%
540
63%
540
34%
988
September16th to endNight
46%
563
20%
1800
14%
563
55%
563
30%
1050
October1st to 15thNight
40%
660
24%
1980
17%
660
46%
660
30%
1203
October16th to endNight
35%
704
18%
2153
11%
704
42%
704
22%
1420
November1st to 15thNight
31%
772
21%
2348
11%
772
42%
772
25%
1486
November16th to endNight
25%
900
15%
2520
7%
900
31%
900
17%
1825
December1st to 15thNight
21%
900
9%
2520
3%
900
27%
900
14%
1939
December16th to endNight
21%
960
10%
2688
3%
960
28%
960
12%
2172

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
14%8%36%5%3445%7%37%
47898
Night
13%8%36%5%34446%40%
47024
Cloud CoverDay
26%7%25%423446%32%
47909
Night
25%7%25%423345%35%
47028
Cloud CoverDay
14%8%36%5%3445%7%37%
47907
Night
13%8%36%5%24446%40%
47028
TransparencyDay
46%5%13%22%10%
47584
Night
44%5%13%23%12%1
46856
SeeingDay
17%8%27%27%13%4
6100
Night
16%9%29%31%11%1
16096

By Month

Percentage Cloud Cover NE (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%10%6%9%7%5%6%45%6%28%
1432
16th to endDay
13%12%6%10%7%35%45%6%23%
1649
February1st to 15thDay
9%12%6%9%5%3445%7%30%
1575
16th to endDay
13%12%37%5%34447%33%
1500
March1st to 15thDay
16%10%36%424446%36%
1897
16th to endDay
19%9%35%6%245%5%7%30%
2157
April1st to 15thDay
18%10%36%5%34346%34%
2151
16th to endDay
22%10%35%5%23445%30%
2226
May1st to 15thDay
19%7%36%5%35%447%31%
2487
16th to endDay
14%6%25%5%345%5%6%39%
2617
June1st to 15thDay
14%5%25%4345%6%7%39%
2520
16th to endDay
10%6%246%35%5%6%8%40%
2520
July1st to 15thDay
6%324435%5%6%8%48%
2520
16th to endDay
7%4245%35%5%7%9%43%
2655
August1st to 15thDay
8%425%5%35%6%6%8%42%
2357
16th to endDay
12%5%2442345%8%45%
2366
September1st to 15thDay
12%4145%33447%47%
2160
16th to endDay
15%6%25%42435%8%40%
1818
October1st to 15thDay
16%5%25%413335%46%
1650
16th to endDay
18%11%345%33335%38%
1718
November1st to 15thDay
13%7%47%425%447%38%
1507
16th to endDay
16%9%45%5%33447%34%
1440
December1st to 15thDay
15%11%5%10%6%36%5%4426%
1440
16th to endDay
19%15%7%10%7%2432420%
1536
January1st to 15thNight
11%9%6%9%7%35%345%31%
2506
16th to endNight
13%12%49%6%45%45%6%26%
2574
February1st to 15thNight
8%11%5%8%7%34445%36%
2285
16th to endNight
11%9%46%434446%38%
1973
March1st to 15thNight
12%9%46%434345%41%
2050
16th to endNight
17%9%35%5%2445%6%34%
2067
April1st to 15thNight
18%9%35%424346%37%
1797
16th to endNight
23%7%25%433346%34%
1732
May1st to 15thNight
21%6%2442345%5%39%
1464
16th to endNight
12%6%245%245%6%7%42%
1496
June1st to 15thNight
12%5%25%4246%5%7%44%
1440
16th to endNight
8%4133245%5%8%51%
1440
July1st to 15thNight
32133235%6%8%57%
1440
16th to endNight
5%21242345%9%55%
1513
August1st to 15thNight
6%3235%35%45%7%51%
1602
16th to endNight
11%424323336%53%
1836
September1st to 15thNight
9%5%13433336%55%
1800
16th to endNight
11%5%2432335%7%49%
1800
October1st to 15thNight
14%6%24322346%49%
1980
16th to endNight
18%7%26%32335%6%40%
2153
November1st to 15thNight
12%7%25%42335%6%45%
2348
16th to endNight
15%10%46%7%33346%32%
2520
December1st to 15thNight
15%12%48%7%34446%27%
2520
16th to endNight
19%14%6%9%5%345%3423%
2688

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
24%7%48%6%4435%5%25%
1432
16th to endDay
27%11%48%6%33345%19%
1649
February1st to 15thDay
24%10%48%422346%28%
1575
16th to endDay
26%10%36%432346%29%
1500
March1st to 15thDay
28%8%25%423335%32%
1908
16th to endDay
32%8%25%5%23345%26%
2157
April1st to 15thDay
31%8%25%5%23335%28%
2151
16th to endDay
36%9%25%42334423%
2226
May1st to 15thDay
32%6%25%5%34346%25%
2487
16th to endDay
29%6%15%5%33435%32%
2617
June1st to 15thDay
29%425%43445%5%31%
2520
16th to endDay
26%5%145%33446%32%
2520
July1st to 15thDay
22%3144235%5%6%39%
2520
16th to endDay
23%31443445%8%36%
2655
August1st to 15thDay
16%415%435%5%6%8%38%
2357
16th to endDay
18%42432345%7%43%
2366
September1st to 15thDay
17%414433446%44%
2160
16th to endDay
21%5%25%423347%37%
1818
October1st to 15thDay
24%5%1442233443%
1650
16th to endDay
25%9%24422335%35%
1718
November1st to 15thDay
24%7%26%323336%35%
1507
16th to endDay
29%7%35%42333431%
1440
December1st to 15thDay
30%9%47%5%345%3422%
1440
16th to endDay
31%13%5%10%6%2232417%
1536
January1st to 15thNight
24%8%48%6%3433428%
2506
16th to endNight
27%11%38%5%34445%21%
2574
February1st to 15thNight
23%10%37%5%2333432%
2278
16th to endNight
24%7%36%423436%32%
1973
March1st to 15thNight
25%7%36%32333436%
2062
16th to endNight
30%8%25%423345%30%
2067
April1st to 15thNight
31%7%24322335%32%
1797
16th to endNight
36%7%15%323235%27%
1732
May1st to 15thNight
34%6%1432234433%
1463
16th to endNight
27%5%24424345%35%
1496
June1st to 15thNight
26%4144245%45%34%
1440
16th to endNight
24%313323447%43%
1440
July1st to 15thNight
19%2332345%7%47%
1440
16th to endNight
20%21242335%8%47%
1513
August1st to 15thNight
14%31343445%6%47%
1602
16th to endNight
17%313322336%50%
1836
September1st to 15thNight
15%413423335%51%
1800
16th to endNight
18%5%23323346%46%
1800
October1st to 15thNight
22%6%23212335%46%
1980
16th to endNight
25%6%25%323245%37%
2153
November1st to 15thNight
24%6%1441234440%
2348
16th to endNight
27%9%35%6%23245%28%
2520
December1st to 15thNight
29%11%37%5%3333422%
2520
16th to endNight
31%13%48%5%2343320%
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
10%10%6%10%6%46%35%6%28%
1432
16th to endDay
13%13%6%9%7%3445%6%23%
1649
February1st to 15thDay
9%12%6%9%6%2446%6%31%
1575
16th to endDay
13%12%36%5%34447%34%
1500
March1st to 15thDay
16%10%36%5%23446%35%
1908
16th to endDay
20%9%25%5%2445%7%30%
2155
April1st to 15thDay
18%10%36%5%34446%34%
2151
16th to endDay
22%9%36%5%24446%29%
2226
May1st to 15thDay
19%7%36%6%35%447%31%
2487
16th to endDay
14%6%26%5%3445%6%38%
2617
June1st to 15thDay
15%5%344345%6%7%39%
2520
16th to endDay
10%6%25%6%445%5%8%40%
2520
July1st to 15thDay
6%3244345%6%9%48%
2520
16th to endDay
7%3245%36%5%7%9%43%
2655
August1st to 15thDay
8%426%5%45%6%6%8%41%
2357
16th to endDay
13%425%3235%48%45%
2366
September1st to 15thDay
12%42443445%7%48%
2160
16th to endDay
15%7%15%5%2435%7%40%
1818
October1st to 15thDay
16%6%24424435%46%
1650
16th to endDay
18%11%34433335%37%
1718
November1st to 15thDay
13%8%47%424447%38%
1507
16th to endDay
15%10%45%5%24446%33%
1440
December1st to 15thDay
16%11%6%9%6%35%5%4426%
1440
16th to endDay
20%15%6%10%7%24325%20%
1536
January1st to 15thNight
11%9%6%9%7%35%345%31%
2506
16th to endNight
13%12%5%9%6%445%5%6%26%
2574
February1st to 15thNight
8%10%6%9%7%34445%36%
2278
16th to endNight
11%9%47%5%34446%38%
1973
March1st to 15thNight
12%9%46%334345%41%
2062
16th to endNight
17%10%36%5%33447%34%
2067
April1st to 15thNight
19%8%35%424346%37%
1797
16th to endNight
23%7%25%423346%34%
1732
May1st to 15thNight
21%6%25%42335%6%39%
1463
16th to endNight
12%5%24425%5%5%7%42%
1496
June1st to 15thNight
11%5%245%245%5%7%44%
1440
16th to endNight
7%4233245%6%8%51%
1440
July1st to 15thNight
321332446%9%56%
1440
16th to endNight
421342336%9%56%
1513
August1st to 15thNight
6%3235%35%5%5%6%51%
1602
16th to endNight
12%424423346%53%
1836
September1st to 15thNight
9%5%13423345%54%
1800
16th to endNight
12%5%3342335%7%49%
1800
October1st to 15thNight
14%6%24323335%49%
1980
16th to endNight
18%7%25%32325%6%40%
2153
November1st to 15thNight
12%7%35%413346%45%
2348
16th to endNight
16%10%47%6%24446%32%
2520
December1st to 15thNight
15%13%48%7%35%446%27%
2520
16th to endNight
19%14%6%9%5%3443423%
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
57%412%17%7%
1433
16th to endDay
61%5%13%14%4
1649
February1st to 15thDay
52%315%18%8%
1576
16th to endDay
51%5%10%24%7%
1500
March1st to 15thDay
49%415%20%8%1
1908
16th to endDay
53%5%14%21%4
2157
April1st to 15thDay
52%410%21%10%1
2151
16th to endDay
56%412%16%9%
2226
May1st to 15thDay
52%413%20%8%
2487
16th to endDay
44%6%11%22%12%2
2621
June1st to 15thDay
42%6%12%25%11%1
2520
16th to endDay
40%5%14%25%12%1
2520
July1st to 15thDay
31%7%16%27%14%1
2371
16th to endDay
33%8%16%24%15%1
2488
August1st to 15thDay
36%6%13%30%11%1
2342
16th to endDay
36%6%15%26%13%1
2366
September1st to 15thDay
36%415%30%13%
2160
16th to endDay
42%5%13%29%8%
1818
October1st to 15thDay
40%411%28%14%
1650
16th to endDay
49%314%24%7%
1718
November1st to 15thDay
45%6%12%19%14%1
1507
16th to endDay
50%6%17%17%7%
1440
December1st to 15thDay
60%7%13%14%5%
1440
16th to endDay
69%49%12%3
1536
January1st to 15thNight
54%411%21%7%
2506
16th to endNight
57%5%13%17%5%
2574
February1st to 15thNight
50%413%22%8%
2288
16th to endNight
46%5%12%25%9%
1973
March1st to 15thNight
45%414%22%10%1
2062
16th to endNight
50%413%23%7%
2067
April1st to 15thNight
47%310%22%14%1
1797
16th to endNight
50%410%18%13%3
1732
May1st to 15thNight
45%5%12%21%13%1
1464
16th to endNight
39%6%12%23%16%1
1498
June1st to 15thNight
37%6%14%27%13%1
1440
16th to endNight
29%6%13%29%17%2
1440
July1st to 15thNight
22%6%13%36%18%1
1360
16th to endNight
23%6%17%30%18%4
1417
August1st to 15thNight
31%5%13%28%18%2
1593
16th to endNight
32%414%28%16%3
1836
September1st to 15thNight
30%411%31%21%
1800
16th to endNight
34%414%30%15%
1800
October1st to 15thNight
36%410%30%16%2
1980
16th to endNight
44%413%23%12%1
2153
November1st to 15thNight
40%413%23%15%1
2348
16th to endNight
53%415%19%6%1
2520
December1st to 15thNight
58%5%12%18%4
2520
16th to endNight
64%5%12%12%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
23%12%35%21%5%2
90
16th to endDay
33%13%31%19%11
96
February1st to 15thDay
16%24%33%22%21
90
16th to endDay
25%12%41%17%2
81
March1st to 15thDay
27%12%40%16%3
90
16th to endDay
32%7%29%18%9%2
141
April1st to 15thDay
25%11%25%27%10%
270
16th to endDay
27%12%28%22%8%1
336
May1st to 15thDay
22%13%32%20%9%1
468
16th to endDay
18%10%28%27%10%4
517
June1st to 15thDay
15%7%28%30%12%4
495
16th to endDay
14%8%30%27%15%3
495
July1st to 15thDay
7%5%24%33%18%10%
475
16th to endDay
9%5%26%32%20%6%
515
August1st to 15thDay
11%223%35%21%6%
493
16th to endDay
17%5%17%30%21%5%
406
September1st to 15thDay
12%5%24%32%18%6%
315
16th to endDay
20%5%26%27%16%4
175
October1st to 15thDay
7%14%30%24%16%6%
90
16th to endDay
26%13%26%22%10%1
96
November1st to 15thDay
5%7%33%37%12%3
90
16th to endDay
38%7%31%15%6%
90
December1st to 15thDay
18%15%37%26%1
90
16th to endDay
32%19%36%9%2
96
January1st to 15thNight
14%14%34%27%8%
900
16th to endNight
19%10%36%26%5%
960
February1st to 15thNight
13%13%36%29%7%
880
16th to endNight
14%13%37%27%7%
711
March1st to 15thNight
16%10%34%28%8%1
622
16th to endNight
20%9%28%30%10%1
576
April1st to 15thNight
23%9%33%28%5%
539
16th to endNight
27%6%30%26%8%
540
May1st to 15thNight
23%9%30%29%6%1
540
16th to endNight
14%5%29%35%13%1
563
June1st to 15thNight
13%5%24%42%14%
540
16th to endNight
10%327%42%16%
540
July1st to 15thNight
3324%39%27%2
510
16th to endNight
5%217%47%24%2
564
August1st to 15thNight
9%116%44%25%2
539
16th to endNight
12%321%32%26%2
573
September1st to 15thNight
12%421%36%17%7%
540
16th to endNight
13%7%25%30%20%1
563
October1st to 15thNight
17%9%29%28%13%1
660
16th to endNight
21%11%25%31%8%
704
November1st to 15thNight
17%11%33%27%8%
772
16th to endNight
20%15%31%23%8%
900
December1st to 15thNight
22%13%34%24%5%
900
16th to endNight
26%10%28%26%7%
960
Page generated at 2017-09-16 16:07:02. Version ac04

Copyright 2017 A. Danko


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