Tufts Bay Campground
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Tufts Bay Campground 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
41%
15630
12%
46725
8%
15597
45%
15597
21%
32371

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
34%
895
8%
2685
4%
895
37%
895
15%
2028
January16th to endNight
26%
960
12%
2777
6%
960
32%
960
14%
2098
February1st to 15thNight
37%
759
10%
2350
7%
759
40%
759
16%
1747
February16th to endNight
43%
632
12%
2025
9%
632
48%
632
17%
1472
March1st to 15thNight
40%
720
13%
2109
9%
720
45%
720
23%
1477
March16th to endNight
37%
696
11%
2040
7%
696
42%
696
16%
1533
April1st to 15thNight
41%
539
14%
1798
9%
539
47%
539
23%
1154
April16th to endNight
37%
540
13%
1535
11%
540
39%
540
19%
1111
May1st to 15thNight
44%
539
11%
1439
6%
539
47%
539
29%
966
May16th to endNight
43%
498
6%
1433
5%
496
45%
496
21%
1011
June1st to 15thNight
44%
360
2%
1107
2%
360
45%
360
23%
737
June16th to endNight
51%
360
0%
1082
0%
360
51%
360
27%
690
July1st to 15thNight
65%
340
2%
1190
2%
340
66%
340
32%
648
July16th to endNight
63%
453
12%
1310
9%
425
66%
425
43%
688
August1st to 15thNight
67%
539
16%
1432
11%
536
70%
536
44%
805
August16th to endNight
61%
573
23%
1755
18%
573
67%
573
39%
961
September1st to 15thNight
55%
540
17%
1800
17%
540
59%
540
29%
1049
September16th to endNight
51%
567
24%
1819
21%
567
59%
567
35%
1013
October1st to 15thNight
43%
660
20%
1980
13%
660
49%
660
26%
1287
October16th to endNight
39%
825
16%
2247
7%
825
45%
825
24%
1571
November1st to 15thNight
33%
875
15%
2450
8%
875
39%
875
21%
1745
November16th to endNight
30%
900
12%
2550
5%
900
36%
900
15%
1944
December1st to 15thNight
28%
900
5%
2806
4%
900
30%
900
10%
2303
December16th to endNight
32%
960
9%
3006
5%
960
36%
960
12%
2333

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
11%8%36%6%35%5%5%7%36%
48071
Night
9%8%47%6%35%45%7%36%
46880
Cloud CoverDay
11%8%36%6%35%5%5%8%35%
48072
Night
9%8%47%6%35%5%5%7%35%
46882
TransparencyDay
45%7%16%21%7%
47728
Night
46%7%15%21%8%
46727
SeeingDay
14%6%25%29%18%4
6177
Night
13%5%28%35%15%1
15644

By Month

Percentage Cloud Cover NW (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
7%13%6%9%10%6%6%5%36%23%
1253
16th to endDay
411%6%10%9%45%5%6%8%27%
1446
February1st to 15thDay
9%12%6%11%8%5%7%6%5%5%23%
1521
16th to endDay
9%11%6%11%10%47%5%46%21%
1448
March1st to 15thDay
7%11%6%12%7%36%45%7%25%
1848
16th to endDay
11%9%5%8%7%45%5%5%8%28%
2183
April1st to 15thDay
10%8%36%6%46%6%7%8%32%
2150
16th to endDay
16%10%47%6%25%346%32%
2424
May1st to 15thDay
11%6%25%5%35%5%5%8%38%
2511
16th to endDay
18%6%35%5%34447%34%
2679
June1st to 15thDay
18%7%344245%6%8%34%
2850
16th to endDay
14%5%24435%5%6%8%37%
2874
July1st to 15thDay
9%41442446%8%49%
2700
16th to endDay
7%31332446%8%53%
2768
August1st to 15thDay
9%5%2432445%8%47%
2520
16th to endDay
10%31332345%8%52%
2446
September1st to 15thDay
11%5%1442345%6%47%
2160
16th to endDay
11%413323338%52%
1845
October1st to 15thDay
16%10%34424446%38%
1650
16th to endDay
11%11%36%6%2445%8%34%
1612
November1st to 15thDay
11%12%5%5%5%3336%6%36%
1408
16th to endDay
11%13%5%9%8%445%5%6%24%
1408
December1st to 15thDay
10%15%6%12%11%47%5%45%17%
1152
16th to endDay
7%12%8%11%10%6%6%5%47%19%
1215
January1st to 15thNight
7%10%5%9%9%46%5%5%7%26%
2685
16th to endNight
6%12%7%10%7%36%5%6%6%27%
2777
February1st to 15thNight
7%12%5%10%8%46%45%6%28%
2340
16th to endNight
6%10%5%11%8%36%47%7%27%
2025
March1st to 15thNight
7%10%37%7%35%5%6%9%33%
2109
16th to endNight
11%10%5%8%6%36%6%6%7%27%
2037
April1st to 15thNight
10%8%346%35%5%5%7%39%
1798
16th to endNight
13%10%36%6%35%45%8%32%
1535
May1st to 15thNight
13%7%25%4245%5%6%42%
1439
16th to endNight
18%5%26%5%3445%6%36%
1433
June1st to 15thNight
15%5%247%345%5%8%37%
1107
16th to endNight
13%4144245%6%9%43%
1082
July1st to 15thNight
6%313335%5%6%9%50%
1260
16th to endNight
421332336%10%58%
1400
August1st to 15thNight
5%31331436%8%57%
1440
16th to endNight
6%32333345%6%57%
1755
September1st to 15thNight
11%5%2441435%6%49%
1800
16th to endNight
11%313313347%54%
1819
October1st to 15thNight
13%7%25%423447%44%
1980
16th to endNight
9%11%35%6%35%446%39%
2247
November1st to 15thNight
13%9%48%5%24447%35%
2450
16th to endNight
9%12%6%9%7%36%45%6%27%
2550
December1st to 15thNight
10%13%7%10%11%46%5%5%6%18%
2806
16th to endNight
5%10%7%12%9%5%6%6%5%7%23%
3006

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
7%13%5%10%11%5%7%446%23%
1253
16th to endDay
5%10%5%11%9%45%5%6%8%27%
1446
February1st to 15thDay
8%12%6%10%7%5%8%6%45%22%
1521
16th to endDay
9%11%5%12%10%47%5%5%7%20%
1448
March1st to 15thDay
7%12%6%11%7%45%45%7%25%
1848
16th to endDay
10%10%5%9%6%46%45%8%28%
2184
April1st to 15thDay
10%7%46%6%36%6%6%9%31%
2150
16th to endDay
16%11%38%5%25%346%31%
2424
May1st to 15thDay
11%6%35%6%35%5%5%9%36%
2511
16th to endDay
18%6%26%5%3445%8%33%
2679
June1st to 15thDay
18%7%35%5%245%6%8%32%
2850
16th to endDay
14%5%245%25%6%7%8%36%
2874
July1st to 15thDay
8%4244245%5%9%47%
2700
16th to endDay
7%31332446%8%51%
2768
August1st to 15thDay
9%5%24425%45%9%46%
2520
16th to endDay
10%32342345%8%51%
2446
September1st to 15thDay
11%5%144235%46%47%
2160
16th to endDay
11%413423338%51%
1845
October1st to 15thDay
16%9%345%24447%38%
1650
16th to endDay
11%11%46%5%2445%8%34%
1612
November1st to 15thDay
11%11%5%6%43436%5%36%
1408
16th to endDay
10%13%49%9%446%5%6%24%
1408
December1st to 15thDay
9%14%7%12%10%5%7%445%17%
1152
16th to endDay
6%13%6%13%9%5%6%6%5%6%19%
1215
January1st to 15thNight
6%10%6%9%9%5%6%6%5%8%25%
2685
16th to endNight
6%11%6%10%7%46%5%7%7%26%
2777
February1st to 15thNight
7%11%5%10%9%46%45%6%27%
2340
16th to endNight
6%10%5%10%8%46%5%7%8%26%
2025
March1st to 15thNight
6%10%37%6%35%5%6%9%33%
2109
16th to endNight
11%10%48%6%35%6%6%8%26%
2040
April1st to 15thNight
9%8%35%5%35%5%5%7%39%
1798
16th to endNight
12%10%46%6%35%5%5%7%33%
1535
May1st to 15thNight
12%8%16%42446%6%41%
1439
16th to endNight
17%6%35%6%345%5%6%36%
1432
June1st to 15thNight
15%5%25%7%3445%10%35%
1107
16th to endNight
12%5%335%245%6%9%42%
1082
July1st to 15thNight
5%323435%5%6%8%50%
1260
16th to endNight
431232346%10%58%
1400
August1st to 15thNight
5%3133235%6%9%56%
1440
16th to endNight
6%323334447%56%
1755
September1st to 15thNight
10%5%245%2445%7%48%
1800
16th to endNight
10%41331335%7%54%
1819
October1st to 15thNight
12%7%35%434347%44%
1980
16th to endNight
9%10%36%6%35%446%38%
2247
November1st to 15thNight
12%9%48%6%3435%7%35%
2450
16th to endNight
9%12%6%9%7%45%5%5%7%26%
2550
December1st to 15thNight
10%13%6%11%10%47%5%5%7%17%
2806
16th to endNight
5%10%7%12%9%47%6%5%7%22%
3006

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
60%6%15%12%4
1253
16th to endDay
52%7%16%16%4
1446
February1st to 15thDay
61%7%13%14%3
1521
16th to endDay
62%7%11%12%5%
1448
March1st to 15thDay
57%7%18%13%3
1848
16th to endDay
53%10%16%16%3
2184
April1st to 15thDay
47%8%16%18%8%
2150
16th to endDay
53%5%14%18%6%1
2424
May1st to 15thDay
42%7%13%26%9%
2511
16th to endDay
49%6%14%17%11%
2683
June1st to 15thDay
47%8%15%21%6%
2850
16th to endDay
42%11%18%24%3
2874
July1st to 15thDay
30%9%21%29%8%
2541
16th to endDay
28%9%21%30%9%1
2595
August1st to 15thDay
34%8%23%24%7%
2504
16th to endDay
29%7%17%30%12%1
2446
September1st to 15thDay
35%7%17%23%14%1
2160
16th to endDay
33%415%33%11%1
1845
October1st to 15thDay
45%6%16%24%6%
1650
16th to endDay
47%7%17%23%3
1612
November1st to 15thDay
48%6%18%19%6%
1408
16th to endDay
57%9%15%15%2
1408
December1st to 15thDay
68%7%12%9%2
1152
16th to endDay
62%7%16%11%1
1215
January1st to 15thNight
54%7%16%16%3
2685
16th to endNight
54%8%14%15%6%
2777
February1st to 15thNight
54%6%14%17%6%
2351
16th to endNight
52%6%15%17%7%
2025
March1st to 15thNight
45%7%19%21%5%
2109
16th to endNight
54%7%15%15%5%
2040
April1st to 15thNight
41%6%16%21%12%1
1798
16th to endNight
50%7%11%17%9%3
1535
May1st to 15thNight
42%412%25%13%1
1440
16th to endNight
47%7%12%17%13%1
1433
June1st to 15thNight
43%6%14%22%11%
1107
16th to endNight
37%7%18%26%7%
1082
July1st to 15thNight
28%8%19%34%9%
1190
16th to endNight
21%7%19%35%13%1
1310
August1st to 15thNight
22%8%24%33%9%1
1432
16th to endNight
25%7%11%34%18%1
1755
September1st to 15thNight
34%6%11%24%17%4
1800
16th to endNight
29%5%11%34%16%1
1819
October1st to 15thNight
40%6%15%26%10%
1980
16th to endNight
45%6%17%23%6%
2247
November1st to 15thNight
48%6%15%19%7%1
2450
16th to endNight
55%7%16%16%4
2550
December1st to 15thNight
65%7%13%11%1
2806
16th to endNight
58%8%14%14%3
3006

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
10%5%21%26%31%5%
60
16th to endDay
16%11%22%29%17%3
81
February1st to 15thDay
17%7%32%30%11%1
90
16th to endDay
20%218%40%14%2
81
March1st to 15thDay
13%11%36%28%8%1
138
16th to endDay
13%11%33%29%10%1
288
April1st to 15thDay
11%16%32%26%9%3
269
16th to endDay
20%9%26%26%16%1
369
May1st to 15thDay
12%8%28%29%17%2
468
16th to endDay
16%9%21%26%17%9%
517
June1st to 15thDay
17%6%28%27%14%3
495
16th to endDay
14%9%23%28%21%2
495
July1st to 15thDay
12%120%31%28%5%
475
16th to endDay
9%424%32%23%6%
515
August1st to 15thDay
10%318%32%25%10%
493
16th to endDay
10%5%20%35%22%5%
346
September1st to 15thDay
19%6%22%30%16%4
315
16th to endDay
13%6%25%31%19%4
180
October1st to 15thDay
31%425%18%16%3
90
16th to endDay
22%429%19%20%3
96
November1st to 15thDay
15%228%33%17%2
90
16th to endDay
20%12%14%23%23%6%
90
December1st to 15thDay
5%138%30%15%8%
72
16th to endDay
14%39%31%7%7%
64
January1st to 15thNight
11%7%29%36%12%
900
16th to endNight
11%10%37%30%8%
960
February1st to 15thNight
11%5%27%35%17%2
767
16th to endNight
9%326%37%17%5%
632
March1st to 15thNight
9%5%31%36%14%1
720
16th to endNight
16%6%27%35%12%1
696
April1st to 15thNight
13%8%30%35%11%
539
16th to endNight
18%7%28%35%9%
540
May1st to 15thNight
15%5%26%34%16%1
540
16th to endNight
20%5%21%30%17%3
498
June1st to 15thNight
18%326%30%18%2
360
16th to endNight
14%323%38%17%2
360
July1st to 15thNight
7%218%44%24%1
340
16th to endNight
5%424%39%24%1
453
August1st to 15thNight
7%217%37%31%4
539
16th to endNight
7%224%37%26%1
573
September1st to 15thNight
13%420%36%23%1
540
16th to endNight
11%5%28%37%16%1
567
October1st to 15thNight
15%429%32%16%1
660
16th to endNight
16%5%29%36%11%1
825
November1st to 15thNight
17%6%32%30%11%1
875
16th to endNight
14%9%33%33%9%
900
December1st to 15thNight
14%6%30%32%14%1
900
16th to endNight
10%5%28%37%15%2
960
Page generated at 2017-09-18 06:38:24. Version ac04

Copyright 2017 A. Danko


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