Lockport
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lockport clear sky chart from 2005-11-06 to 2024-02-20.

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
36%
24741
16%
80540
10%
24638
43%
24638
20%
55173

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 10thNight
20%
944
10%
4402
3%
926
29%
926
10%
3248
January11th to 20thNight
19%
950
9%
4401
4%
930
25%
930
8%
3506
January21st to endNight
19%
1037
7%
4747
3%
1023
25%
1023
8%
3803
February1st to 10thNight
19%
898
12%
2418
3%
898
25%
898
17%
1807
February11th to 20thNight
24%
739
19%
2214
8%
739
34%
739
19%
1530
February21st to endNight
20%
592
17%
1776
5%
592
31%
592
17%
1279
March1st to 10thNight
23%
720
12%
2160
7%
720
28%
720
16%
1554
March11th to 20thNight
29%
707
20%
2122
10%
707
38%
707
24%
1361
March21st to endNight
27%
594
14%
1980
10%
594
34%
594
15%
1438
April1st to 10thNight
27%
540
16%
1800
10%
540
37%
540
21%
1176
April11th to 20thNight
29%
533
19%
1775
12%
533
40%
533
21%
1175
April21st to endNight
30%
540
15%
1706
6%
540
39%
540
19%
1184
May1st to 10thNight
34%
540
15%
1620
9%
540
40%
540
23%
1112
May11th to 20thNight
41%
531
17%
1489
9%
531
47%
531
25%
994
May21st to endNight
47%
583
16%
1551
9%
582
51%
582
29%
1046
June1st to 10thNight
53%
540
18%
1440
10%
540
59%
540
36%
899
June11th to 20thNight
51%
540
20%
1440
13%
540
57%
540
36%
878
June21st to endNight
48%
540
17%
1440
10%
540
53%
540
30%
958
July1st to 10thNight
65%
525
16%
1400
12%
525
67%
525
38%
856
July11th to 20thNight
62%
522
22%
1392
16%
522
66%
522
43%
813
July21st to endNight
68%
591
23%
1487
17%
558
72%
558
44%
865
August1st to 10thNight
72%
537
22%
1480
20%
534
74%
534
39%
885
August11th to 20thNight
70%
534
22%
1767
22%
534
74%
534
37%
956
August21st to endNight
65%
594
24%
1980
24%
594
70%
594
37%
1062
September1st to 10thNight
60%
540
24%
1800
23%
540
65%
540
33%
1014
September11th to 20thNight
63%
638
33%
1898
29%
638
68%
638
39%
1068
September21st to endNight
52%
720
23%
1980
17%
720
57%
720
33%
1239
October1st to 10thNight
50%
720
25%
2018
19%
720
54%
720
33%
1231
October11th to 20thNight
32%
720
22%
2168
11%
720
44%
720
25%
1371
October21st to endNight
27%
792
17%
2574
10%
792
36%
792
19%
1728
November1st to 10thNight
29%
740
26%
2406
16%
740
43%
740
26%
1442
November11th to 20thNight
24%
760
18%
2470
9%
760
36%
760
19%
1646
November21st to endNight
22%
802
19%
2512
9%
802
34%
802
19%
1716
December1st to 10thNight
21%
950
13%
2660
5%
950
28%
950
18%
1952
December11th to 20thNight
22%
950
14%
3216
4%
948
29%
948
14%
2354
December21st to endNight
15%
1038
6%
4851
3%
1026
22%
1026
6%
4027

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%9%47%6%35%5%5%7%35%
78320
Night
15%10%47%5%3445%6%37%
80925
TransparencyDay
47%7%12%21%12%2
78021
Night
47%6%11%21%13%2
80745
SeeingDay
17%11%30%24%13%5%
14730
Night
18%10%30%29%12%1
24766

By Month

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 10thDay
14%13%8%9%7%5%45%5%5%26%
2527
11th to 20thDay
14%15%6%13%7%35%8%7%417%
2530
21st to endDay
19%24%7%11%6%2334417%
2878
February1st to 10thDay
17%13%5%8%6%46%5%46%25%
1761
11th to 20thDay
15%10%5%8%8%345%45%34%
1838
21st to endDay
18%13%6%9%5%33446%29%
1480
March1st to 10thDay
17%14%5%6%7%35%35%5%30%
1800
11th to 20thDay
14%9%37%7%45%5%5%6%35%
1852
21st to endDay
21%11%5%8%7%36%446%25%
2376
April1st to 10thDay
16%12%5%7%5%35%45%7%31%
2160
11th to 20thDay
17%9%36%6%35%5%6%7%35%
2134
21st to endDay
21%9%37%6%35%45%6%33%
2254
May1st to 10thDay
19%8%36%6%35%6%6%8%30%
2340
11th to 20thDay
19%9%35%5%45%46%7%34%
2403
21st to endDay
14%6%36%6%35%6%6%8%38%
2725
June1st to 10thDay
10%5%25%5%35%5%6%8%45%
2520
11th to 20thDay
9%5%25%6%36%5%6%8%45%
2520
21st to endDay
11%5%26%6%46%6%7%9%37%
2520
July1st to 10thDay
7%435%5%35%6%6%10%46%
2520
11th to 20thDay
10%426%5%35%5%7%8%44%
2520
21st to endDay
7%5%26%6%35%6%7%10%43%
2743
August1st to 10thDay
7%426%6%45%6%7%10%42%
2449
11th to 20thDay
9%425%5%35%6%7%8%44%
2130
21st to endDay
8%3245%35%6%6%11%47%
2376
September1st to 10thDay
12%5%25%435%46%8%46%
2160
11th to 20thDay
12%3244345%5%8%51%
2044
21st to endDay
10%6%35%5%25%6%5%9%45%
1980
October1st to 10thDay
13%7%25%5%345%5%6%46%
1940
11th to 20thDay
19%8%37%5%345%5%6%36%
1792
21st to endDay
21%8%46%6%34446%35%
1782
November1st to 10thDay
12%8%35%42435%7%45%
1672
11th to 20thDay
17%9%5%8%5%25%45%7%34%
1710
21st to endDay
18%10%48%5%3443436%
1663
December1st to 10thDay
15%13%38%7%45%5%35%30%
1520
11th to 20thDay
14%13%6%10%5%35%5%5%5%29%
1918
21st to endDay
21%23%7%12%7%3433313%
2783
January1st to 10thNight
15%15%8%9%6%4444428%
4428
11th to 20thNight
15%18%8%10%7%445%6%419%
4440
21st to endNight
22%16%8%9%6%3333421%
4788
February1st to 10thNight
16%14%5%8%7%24436%31%
2418
11th to 20thNight
15%10%37%6%445%46%36%
2213
21st to endNight
19%11%47%5%34345%34%
1776
March1st to 10thNight
16%11%5%6%6%36%44434%
2160
11th to 20thNight
13%7%45%5%35%45%7%42%
2122
21st to endNight
20%10%46%6%3445%6%31%
1980
April1st to 10thNight
15%9%46%43445%8%39%
1800
11th to 20thNight
19%8%45%5%2345%6%39%
1775
21st to endNight
19%6%36%5%45%5%5%7%35%
1706
May1st to 10thNight
16%7%36%5%35%46%9%35%
1620
11th to 20thNight
15%7%25%6%345%6%8%40%
1488
21st to endNight
12%5%346%35%6%7%9%40%
1551
June1st to 10thNight
10%425%5%345%5%6%50%
1440
11th to 20thNight
9%435%4345%6%10%48%
1440
21st to endNight
11%5%26%6%35%6%6%9%41%
1440
July1st to 10thNight
6%5%25%4346%5%10%49%
1440
11th to 20thNight
6%425%4245%5%10%53%
1440
21st to endNight
43245%345%9%9%53%
1575
August1st to 10thNight
5%425%5%35%6%6%10%50%
1489
11th to 20thNight
7%315%4245%6%9%53%
1767
21st to endNight
8%324435%45%8%55%
1980
September1st to 10thNight
11%5%35%42345%7%52%
1800
11th to 20thNight
9%42343435%8%55%
1898
21st to endNight
10%5%26%5%35%6%6%7%46%
1980
October1st to 10thNight
11%5%25%424447%51%
2018
11th to 20thNight
18%8%34423446%45%
2168
21st to endNight
21%8%37%42435%6%37%
2574
November1st to 10thNight
13%7%35%43345%6%49%
2406
11th to 20thNight
15%9%47%6%3445%6%37%
2470
21st to endNight
18%9%47%6%33446%38%
2512
December1st to 10thNight
16%11%5%7%6%3445%6%32%
2660
11th to 20thNight
16%14%6%8%5%3344432%
3279
21st to endNight
24%18%6%10%6%3444416%
4884

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 10thDay
59%6%13%16%6%
2528
11th to 20thDay
65%5%9%12%8%1
2530
21st to endDay
70%48%12%5%
2878
February1st to 10thDay
59%6%11%14%8%2
1761
11th to 20thDay
52%6%10%22%9%2
1848
21st to endDay
57%6%10%19%7%2
1480
March1st to 10thDay
57%6%10%20%7%1
1800
11th to 20thDay
48%6%13%21%10%1
1852
21st to endDay
61%5%11%17%5%1
2376
April1st to 10thDay
52%6%11%19%11%1
2160
11th to 20thDay
47%7%10%20%12%4
2134
21st to endDay
51%5%13%16%12%2
2254
May1st to 10thDay
50%8%12%21%8%
2340
11th to 20thDay
49%7%12%21%12%1
2407
21st to endDay
43%8%12%19%16%2
2725
June1st to 10thDay
35%9%11%25%17%2
2520
11th to 20thDay
36%7%11%24%20%3
2520
21st to endDay
41%10%14%20%13%2
2520
July1st to 10thDay
33%7%14%27%15%3
2451
11th to 20thDay
34%9%16%24%16%2
2445
21st to endDay
34%8%17%24%14%3
2591
August1st to 10thDay
33%9%16%28%11%2
2434
11th to 20thDay
34%9%15%25%16%1
2130
21st to endDay
30%8%14%25%19%4
2376
September1st to 10thDay
35%8%13%23%17%4
2160
11th to 20thDay
32%5%12%28%19%3
2044
21st to endDay
36%6%11%25%20%2
1980
October1st to 10thDay
39%6%12%25%16%3
1940
11th to 20thDay
47%7%11%21%13%1
1792
21st to endDay
50%5%12%22%10%2
1782
November1st to 10thDay
39%5%14%24%16%2
1672
11th to 20thDay
50%5%12%21%11%1
1710
21st to endDay
53%410%23%10%
1663
December1st to 10thDay
55%6%12%19%8%1
1520
11th to 20thDay
55%6%12%19%7%1
1915
21st to endDay
77%48%8%3
2783
January1st to 10thNight
59%6%11%15%8%
4428
11th to 20thNight
67%411%11%6%
4440
21st to endNight
67%49%13%5%
4788
February1st to 10thNight
56%411%17%10%2
2418
11th to 20thNight
49%5%10%22%13%1
2214
21st to endNight
53%5%10%18%11%3
1776
March1st to 10thNight
53%5%11%20%9%1
2160
11th to 20thNight
42%5%13%20%16%3
2122
21st to endNight
54%6%11%18%9%1
1980
April1st to 10thNight
45%5%13%23%13%2
1800
11th to 20thNight
46%5%9%20%16%4
1775
21st to endNight
48%7%11%19%13%3
1706
May1st to 10thNight
46%6%13%24%11%
1620
11th to 20thNight
41%8%13%22%15%1
1489
21st to endNight
38%9%14%19%17%3
1552
June1st to 10thNight
33%6%11%26%19%4
1440
11th to 20thNight
32%7%13%24%22%2
1440
21st to endNight
38%9%15%21%16%3
1440
July1st to 10thNight
30%8%16%25%17%5%
1400
11th to 20thNight
27%6%15%28%21%4
1392
21st to endNight
25%7%18%26%18%6%
1487
August1st to 10thNight
27%9%17%29%16%2
1480
11th to 20thNight
26%8%17%27%21%2
1767
21st to endNight
27%6%13%28%21%5%
1980
September1st to 10thNight
32%5%12%25%23%3
1800
11th to 20thNight
28%5%9%30%25%3
1898
21st to endNight
35%6%12%28%17%3
1980
October1st to 10thNight
34%6%10%26%21%3
2018
11th to 20thNight
40%5%10%24%19%2
2168
21st to endNight
48%410%23%13%1
2574
November1st to 10thNight
38%5%9%26%19%3
2406
11th to 20thNight
48%412%22%13%2
2470
21st to endNight
49%412%23%11%
2512
December1st to 10thNight
52%6%11%21%9%1
2660
11th to 20thNight
56%412%18%9%1
3281
21st to endNight
71%5%9%11%4
4884

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 10thDay
23%13%36%23%6%
270
11th to 20thDay
25%20%34%16%41
270
21st to endDay
24%15%38%19%4
297
February1st to 10thDay
23%20%39%14%3
270
11th to 20thDay
25%20%32%19%31
267
21st to endDay
27%21%40%10%2
198
March1st to 10thDay
26%19%39%14%2
240
11th to 20thDay
27%14%36%17%5%1
264
21st to endDay
31%16%27%18%7%2
462
April1st to 10thDay
22%17%30%23%8%1
420
11th to 20thDay
23%19%26%20%11%1
412
21st to endDay
24%15%34%18%8%1
420
May1st to 10thDay
24%13%31%21%9%3
423
11th to 20thDay
20%9%35%22%11%3
549
21st to endDay
15%9%32%23%15%6%
679
June1st to 10thDay
9%9%31%30%16%5%
630
11th to 20thDay
14%7%30%28%17%4
630
21st to endDay
12%10%32%29%13%4
630
July1st to 10thDay
7%423%30%21%15%
621
11th to 20thDay
12%6%26%29%18%10%
618
21st to endDay
8%428%34%21%6%
684
August1st to 10thDay
8%221%34%25%11%
568
11th to 20thDay
10%417%31%24%13%
439
21st to endDay
7%319%37%23%10%
495
September1st to 10thDay
12%6%23%31%22%5%
450
11th to 20thDay
11%419%32%24%11%
450
21st to endDay
12%9%24%27%20%6%
450
October1st to 10thDay
17%8%27%29%15%4
410
11th to 20thDay
18%26%33%17%6%
270
21st to endDay
32%12%35%15%5%
297
November1st to 10thDay
16%15%38%20%7%3
270
11th to 20thDay
26%17%35%16%6%1
270
21st to endDay
25%9%42%18%5%
270
December1st to 10thDay
19%20%38%16%6%1
270
11th to 20thDay
21%16%41%19%4
270
21st to endDay
27%21%36%14%2
297
January1st to 10thNight
20%15%37%23%5%
950
11th to 20thNight
22%17%34%21%5%1
950
21st to endNight
21%13%34%27%4
1045
February1st to 10thNight
24%13%36%23%3
898
11th to 20thNight
21%13%36%26%4
742
21st to endNight
24%15%36%21%4
592
March1st to 10thNight
21%15%37%22%6%
720
11th to 20thNight
18%11%38%27%6%1
707
21st to endNight
26%11%32%24%7%1
594
April1st to 10thNight
19%13%36%25%7%
540
11th to 20thNight
21%13%33%24%8%1
533
21st to endNight
22%9%34%28%7%1
540
May1st to 10thNight
19%7%35%30%9%
540
11th to 20thNight
18%5%31%33%13%
531
21st to endNight
12%5%28%36%19%
584
June1st to 10thNight
11%327%45%14%1
540
11th to 20thNight
11%427%44%13%1
540
21st to endNight
12%5%26%38%19%1
540
July1st to 10thNight
7%318%41%28%4
525
11th to 20thNight
6%420%39%28%3
522
21st to endNight
5%218%49%25%2
591
August1st to 10thNight
5%112%49%28%4
537
11th to 20thNight
7%213%40%33%4
534
21st to endNight
8%119%39%30%3
594
September1st to 10thNight
11%418%37%27%4
540
11th to 20thNight
10%420%35%27%5%
638
21st to endNight
12%7%23%34%21%3
720
October1st to 10thNight
13%6%26%35%18%2
720
11th to 20thNight
21%13%30%27%9%
720
21st to endNight
27%11%30%25%7%
792
November1st to 10thNight
16%12%39%22%10%1
740
11th to 20thNight
20%16%33%25%6%
760
21st to endNight
22%11%39%21%6%
802
December1st to 10thNight
23%13%37%24%4
950
11th to 20thNight
24%12%35%24%5%
950
21st to endNight
31%14%33%21%2
1045
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