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 2005-11-06 to 2024-04-10.

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 Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(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

By Month

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 Forecast	Data Points
Cloud Cover	Day	9% 8% 4 7% 6% 4 5% 5% 6% 8% 38%	82460
	Night	8% 8% 4 8% 7% 4 6% 5% 6% 8% 37%	86289
Transparency	Day	43% 8% 17% 22% 9% 1	82168
	Night	43% 8% 16% 22% 9% 1	86161
Seeing	Day	12% 8% 27% 31% 18% 5%	14921
	Night	11% 7% 30% 36% 14% 1	24505

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	7% 12% 5% 9% 12% 6% 6% 6% 4 5% 27%	2219
	11th to 20th	Day	4 8% 4 10% 10% 8% 12% 9% 6% 8% 22%	2199
	21st to end	Day	5% 10% 4 8% 9% 4 6% 5% 6% 8% 34%	2708
February	1st to 10th	Day	8% 11% 6% 12% 7% 5% 7% 6% 6% 7% 24%	1625
	11th to 20th	Day	8% 12% 5% 9% 9% 4 7% 6% 5% 6% 29%	1665
	21st to end	Day	6% 9% 6% 11% 10% 5% 7% 7% 7% 7% 24%	1455
March	1st to 10th	Day	7% 12% 5% 11% 9% 4 6% 5% 5% 6% 29%	3130
	11th to 20th	Day	5% 10% 7% 11% 6% 3 4 4 5% 8% 36%	3457
	21st to end	Day	6% 9% 5% 10% 9% 4 6% 6% 6% 8% 31%	4010
April	1st to 10th	Day	7% 8% 3 7% 7% 4 6% 6% 8% 8% 35%	2269
	11th to 20th	Day	11% 11% 4 9% 7% 3 6% 5% 6% 9% 29%	2198
	21st to end	Day	15% 9% 4 7% 5% 3 4 4 5% 6% 36%	2488
May	1st to 10th	Day	12% 6% 3 6% 6% 4 6% 5% 7% 8% 37%	2520
	11th to 20th	Day	8% 5% 3 6% 6% 3 6% 6% 6% 8% 44%	2478
	21st to end	Day	18% 7% 2 6% 5% 3 4 5% 5% 8% 38%	2817
June	1st to 10th	Day	14% 6% 3 5% 5% 3 5% 5% 6% 8% 39%	2834
	11th to 20th	Day	19% 7% 3 5% 5% 3 5% 5% 7% 8% 34%	2880
	21st to end	Day	9% 5% 2 5% 5% 3 6% 5% 7% 10% 44%	2873
July	1st to 10th	Day	6% 4 1 4 4 3 4 5% 7% 10% 52%	2700
	11th to 20th	Day	10% 4 2 4 5% 3 4 5% 6% 8% 49%	2700
	21st to end	Day	5% 3 2 3 3 3 4 4 6% 8% 58%	2822
August	1st to 10th	Day	8% 4 2 4 4 3 5% 5% 6% 8% 52%	2507
	11th to 20th	Day	9% 5% 2 4 5% 3 5% 5% 6% 9% 48%	2409
	21st to end	Day	12% 4 1 3 4 2 3 4 5% 8% 52%	2499
September	1st to 10th	Day	10% 5% 2 5% 4 3 4 5% 6% 8% 48%	2160
	11th to 20th	Day	13% 6% 2 5% 5% 3 4 4 4 8% 45%	2160
	21st to end	Day	11% 5% 2 3 4 3 3 4 4 9% 53%	1916
October	1st to 10th	Day	14% 9% 3 5% 4 3 3 4 4 6% 44%	1800
	11th to 20th	Day	9% 9% 3 6% 6% 3 5% 4 5% 7% 41%	1782
	21st to end	Day	10% 10% 5% 9% 6% 3 5% 5% 5% 9% 33%	1756
November	1st to 10th	Day	15% 15% 5% 7% 6% 5% 4 4 5% 5% 30%	1488
	11th to 20th	Day	6% 13% 4 13% 8% 5% 5% 5% 7% 6% 28%	1520
	21st to end	Day	9% 11% 6% 10% 8% 4 6% 6% 6% 7% 27%	1469
December	1st to 10th	Day	7% 13% 4 10% 11% 5% 7% 7% 6% 6% 25%	1254
	11th to 20th	Day	7% 10% 5% 11% 10% 5% 7% 5% 5% 7% 28%	1439
	21st to end	Day	5% 8% 4 7% 6% 4 5% 5% 5% 7% 44%	2254
January	1st to 10th	Night	4 10% 6% 13% 9% 5% 6% 6% 7% 8% 27%	4726
	11th to 20th	Night	4 6% 5% 13% 12% 7% 9% 8% 6% 6% 23%	4699
	21st to end	Night	6% 11% 4 8% 7% 4 6% 5% 6% 7% 35%	4954
February	1st to 10th	Night	8% 11% 5% 10% 9% 4 6% 7% 6% 8% 26%	2570
	11th to 20th	Night	6% 11% 5% 11% 7% 4 7% 4 7% 8% 30%	2402
	21st to end	Night	4 7% 4 10% 9% 4 8% 6% 8% 9% 32%	1998
March	1st to 10th	Night	6% 10% 4 11% 10% 5% 6% 5% 7% 8% 27%	3734
	11th to 20th	Night	5% 9% 4 7% 7% 4 6% 6% 6% 9% 35%	3505
	21st to end	Night	6% 7% 5% 11% 9% 4 6% 7% 7% 9% 29%	3637
April	1st to 10th	Night	8% 8% 3 5% 6% 4 5% 6% 5% 9% 42%	1900
	11th to 20th	Night	11% 11% 4 8% 7% 4 5% 6% 6% 7% 31%	1711
	21st to end	Night	13% 9% 3 6% 6% 4 5% 6% 5% 8% 35%	1472
May	1st to 10th	Night	13% 8% 3 6% 5% 3 5% 5% 6% 5% 42%	1440
	11th to 20th	Night	10% 6% 3 5% 4 3 4 5% 6% 8% 47%	1418
	21st to end	Night	18% 5% 2 6% 4 4 5% 5% 6% 8% 37%	1456
June	1st to 10th	Night	12% 5% 2 4 7% 3 4 4 6% 9% 43%	1123
	11th to 20th	Night	16% 5% 2 6% 7% 4 4 6% 6% 9% 34%	1080
	21st to end	Night	9% 4 2 4 4 3 4 5% 6% 10% 49%	1083
July	1st to 10th	Night	6% 3 2 3 3 3 5% 5% 6% 10% 53%	1260
	11th to 20th	Night	6% 4 2 4 4 2 4 4 7% 9% 54%	1260
	21st to end	Night	3 2 1 3 3 2 4 4 6% 9% 64%	1494
August	1st to 10th	Night	5% 3 1 3 3 1 4 4 6% 8% 59%	1432
	11th to 20th	Night	5% 3 1 4 4 4 4 4 6% 8% 56%	1490
	21st to end	Night	8% 4 2 3 4 3 4 5% 5% 6% 56%	1856
September	1st to 10th	Night	9% 4 2 5% 5% 3 4 4 6% 7% 50%	1800
	11th to 20th	Night	11% 6% 3 4 5% 2 4 4 6% 8% 49%	1800
	21st to end	Night	11% 5% 2 3 4 2 4 4 5% 8% 53%	2042
October	1st to 10th	Night	14% 7% 2 6% 4 2 4 4 5% 8% 44%	2160
	11th to 20th	Night	7% 8% 3 7% 5% 3 3 4 4 6% 51%	2160
	21st to end	Night	9% 12% 4 8% 6% 4 5% 5% 5% 7% 35%	2596
November	1st to 10th	Night	15% 12% 5% 9% 6% 3 5% 5% 4 5% 30%	2590
	11th to 20th	Night	6% 11% 5% 12% 8% 4 6% 5% 6% 7% 29%	2660
	21st to end	Night	8% 11% 7% 10% 7% 3 5% 5% 6% 8% 30%	2707
December	1st to 10th	Night	8% 10% 6% 11% 11% 5% 7% 5% 5% 6% 27%	2924
	11th to 20th	Night	9% 11% 6% 11% 9% 4 7% 6% 6% 7% 24%	3753
	21st to end	Night	4 6% 3 6% 6% 3 4 4 5% 6% 52%	5397

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	58% 7% 14% 14% 7%	2219
	11th to 20th	Day	57% 10% 14% 15% 4 1	2220
	21st to end	Day	46% 9% 19% 22% 5%	2708
February	1st to 10th	Day	58% 7% 13% 16% 6%	1625
	11th to 20th	Day	54% 7% 14% 16% 9% 1	1674
	21st to end	Day	55% 8% 13% 17% 6%	1455
March	1st to 10th	Day	54% 7% 20% 13% 6%	3130
	11th to 20th	Day	45% 11% 20% 18% 6%	3458
	21st to end	Day	47% 10% 17% 20% 6%	4010
April	1st to 10th	Day	42% 9% 17% 22% 10%	2269
	11th to 20th	Day	52% 7% 15% 17% 7% 2	2198
	21st to end	Day	48% 6% 15% 22% 7% 1	2488
May	1st to 10th	Day	42% 8% 13% 25% 10% 1	2520
	11th to 20th	Day	37% 8% 14% 26% 14%	2482
	21st to end	Day	45% 7% 15% 22% 11% 1	2817
June	1st to 10th	Day	41% 8% 16% 24% 10% 1	2834
	11th to 20th	Day	46% 9% 16% 21% 8% 1	2880
	21st to end	Day	33% 11% 20% 27% 7% 1	2873
July	1st to 10th	Day	25% 10% 22% 31% 10% 1	2626
	11th to 20th	Day	31% 10% 20% 27% 11% 1	2619
	21st to end	Day	23% 8% 20% 34% 13% 1	2665
August	1st to 10th	Day	29% 9% 23% 26% 12% 1	2491
	11th to 20th	Day	33% 10% 19% 28% 9% 1	2409
	21st to end	Day	31% 6% 15% 31% 15% 1	2499
September	1st to 10th	Day	33% 8% 18% 25% 14% 2	2160
	11th to 20th	Day	38% 7% 16% 27% 10% 2	2160
	21st to end	Day	32% 5% 15% 32% 14% 2	1916
October	1st to 10th	Day	41% 7% 17% 26% 9%	1800
	11th to 20th	Day	41% 6% 14% 28% 10% 1	1782
	21st to end	Day	48% 8% 16% 22% 6%	1756
November	1st to 10th	Day	55% 6% 14% 17% 7% 1	1488
	11th to 20th	Day	53% 9% 15% 16% 5%	1520
	21st to end	Day	54% 9% 17% 17% 3	1469
December	1st to 10th	Day	57% 9% 15% 14% 5%	1254
	11th to 20th	Day	55% 8% 21% 10% 6%	1440
	21st to end	Day	38% 6% 15% 21% 14% 6%	2254
January	1st to 10th	Night	51% 10% 19% 16% 4	4726
	11th to 20th	Night	58% 7% 15% 14% 6% 1	4740
	21st to end	Night	46% 9% 19% 22% 4	4954
February	1st to 10th	Night	53% 7% 14% 19% 7%	2570
	11th to 20th	Night	49% 8% 14% 17% 11% 1	2403
	21st to end	Night	44% 8% 15% 23% 9%	1998
March	1st to 10th	Night	50% 9% 19% 19% 4	3734
	11th to 20th	Night	41% 11% 23% 18% 7%	3505
	21st to end	Night	47% 9% 17% 18% 9%	3637
April	1st to 10th	Night	38% 7% 16% 24% 14% 1	1900
	11th to 20th	Night	50% 7% 12% 18% 10% 3	1711
	21st to end	Night	47% 8% 13% 22% 9% 1	1472
May	1st to 10th	Night	41% 6% 13% 24% 15% 1	1440
	11th to 20th	Night	34% 7% 14% 26% 17% 2	1418
	21st to end	Night	43% 8% 14% 20% 15%	1456
June	1st to 10th	Night	36% 7% 15% 29% 13% 1	1123
	11th to 20th	Night	45% 8% 14% 20% 12% 1	1080
	21st to end	Night	30% 9% 21% 29% 10% 1	1083
July	1st to 10th	Night	26% 7% 22% 34% 11%	1225
	11th to 20th	Night	25% 9% 19% 31% 15%	1218
	21st to end	Night	18% 7% 17% 40% 16% 2	1411
August	1st to 10th	Night	20% 9% 22% 35% 13% 2	1424
	11th to 20th	Night	24% 8% 18% 34% 14% 2	1490
	21st to end	Night	26% 8% 12% 33% 19% 2	1856
September	1st to 10th	Night	32% 7% 13% 25% 18% 5%	1800
	11th to 20th	Night	33% 8% 15% 28% 14% 3	1800
	21st to end	Night	29% 6% 12% 33% 17% 2	2042
October	1st to 10th	Night	39% 7% 16% 27% 11%	2160
	11th to 20th	Night	36% 5% 17% 29% 12% 1	2160
	21st to end	Night	49% 7% 14% 22% 7% 1	2596
November	1st to 10th	Night	55% 7% 13% 16% 7% 1	2590
	11th to 20th	Night	52% 8% 18% 16% 6%	2660
	21st to end	Night	50% 9% 18% 20% 4	2707
December	1st to 10th	Night	56% 7% 15% 16% 6%	2924
	11th to 20th	Night	57% 9% 16% 14% 4	3751
	21st to end	Night	33% 5% 13% 27% 15% 6%	5397

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	11% 4 27% 32% 21% 6%	180
	11th to 20th	Day	12% 8% 27% 28% 23% 1	180
	21st to end	Day	9% 11% 28% 33% 17% 2	275
February	1st to 10th	Day	13% 12% 29% 33% 12% 1	270
	11th to 20th	Day	9% 7% 31% 31% 16% 6%	270
	21st to end	Day	8% 6% 26% 34% 22% 4	225
March	1st to 10th	Day	11% 10% 29% 33% 15% 2	270
	11th to 20th	Day	9% 12% 32% 31% 14% 3	441
	21st to end	Day	11% 8% 32% 30% 16% 2	506
April	1st to 10th	Day	8% 14% 34% 28% 12% 3	457
	11th to 20th	Day	15% 14% 32% 26% 10% 3	412
	21st to end	Day	16% 10% 28% 33% 12% 1	568
May	1st to 10th	Day	11% 8% 25% 27% 23% 5%	603
	11th to 20th	Day	9% 8% 25% 32% 18% 7%	625
	21st to end	Day	15% 9% 22% 26% 22% 6%	679
June	1st to 10th	Day	12% 9% 28% 31% 16% 4	630
	11th to 20th	Day	19% 11% 28% 25% 13% 3	630
	21st to end	Day	8% 8% 23% 31% 23% 6%	630
July	1st to 10th	Day	8% 3 22% 37% 24% 6%	621
	11th to 20th	Day	12% 4 26% 30% 22% 6%	618
	21st to end	Day	6% 5% 24% 31% 25% 9%	684
August	1st to 10th	Day	9% 4 20% 37% 22% 9%	626
	11th to 20th	Day	9% 7% 19% 32% 26% 7%	547
	21st to end	Day	13% 4 22% 31% 22% 7%	495
September	1st to 10th	Day	14% 7% 30% 28% 17% 4	450
	11th to 20th	Day	16% 9% 23% 33% 18% 2	450
	21st to end	Day	15% 8% 27% 30% 16% 3	320
October	1st to 10th	Day	17% 6% 25% 24% 23% 5%	270
	11th to 20th	Day	10% 9% 32% 28% 18% 3	270
	21st to end	Day	13% 11% 40% 23% 11% 2	297
November	1st to 10th	Day	21% 9% 28% 26% 12% 4	270
	11th to 20th	Day	13% 11% 31% 31% 13% 1	270
	21st to end	Day	9% 10% 32% 36% 10% 3	270
December	1st to 10th	Day	7% 8% 30% 35% 15% 5%	234
	11th to 20th	Day	7% 10% 42% 31% 9% 1	180
	21st to end	Day	11% 2 31% 33% 18% 6%	198
January	1st to 10th	Night	8% 8% 34% 37% 12% 1	950
	11th to 20th	Night	11% 9% 34% 36% 9% 1	950
	21st to end	Night	11% 9% 36% 33% 11% 1	1045
February	1st to 10th	Night	12% 6% 29% 37% 15% 1	860
	11th to 20th	Night	10% 8% 31% 36% 13% 2	744
	21st to end	Night	5% 4 23% 42% 21% 5%	628
March	1st to 10th	Night	10% 6% 32% 36% 14% 1	760
	11th to 20th	Night	9% 6% 33% 37% 14% 1	760
	21st to end	Night	12% 6% 30% 39% 11% 2	722
April	1st to 10th	Night	10% 9% 29% 38% 12% 1	570
	11th to 20th	Night	15% 10% 33% 33% 8%	533
	21st to end	Night	17% 9% 32% 34% 9%	540
May	1st to 10th	Night	14% 6% 24% 38% 16% 1	540
	11th to 20th	Night	13% 6% 28% 31% 20% 2	531
	21st to end	Night	19% 6% 22% 32% 18% 3	488
June	1st to 10th	Night	14% 7% 28% 32% 18% 3	360
	11th to 20th	Night	18% 6% 26% 35% 14% 2	360
	21st to end	Night	10% 4 22% 44% 19% 3	360
July	1st to 10th	Night	7% 3 22% 45% 21% 1	350
	11th to 20th	Night	9% 4 25% 43% 19% 1	348
	21st to end	Night	3 5% 24% 43% 23% 2	509
August	1st to 10th	Night	7% 4 23% 41% 23% 4	537
	11th to 20th	Night	6% 3 19% 41% 30% 1	534
	21st to end	Night	8% 4 25% 36% 25% 1	594
September	1st to 10th	Night	12% 5% 25% 38% 19% 1	540
	11th to 20th	Night	13% 5% 20% 42% 18% 1	540
	21st to end	Night	12% 6% 31% 37% 13% 1	652
October	1st to 10th	Night	17% 6% 27% 33% 17% 1	720
	11th to 20th	Night	10% 6% 32% 36% 14% 2	720
	21st to end	Night	14% 9% 34% 34% 8% 1	990
November	1st to 10th	Night	21% 7% 32% 31% 8% 1	925
	11th to 20th	Night	11% 9% 33% 34% 12% 2	950
	21st to end	Night	12% 8% 39% 32% 8% 1	950
December	1st to 10th	Night	10% 6% 33% 34% 15% 2	950
	11th to 20th	Night	12% 9% 32% 35% 11% 1	950
	21st to end	Night	11% 5% 30% 38% 13% 2	1045

Page generated at 2024-04-07 07:28:10. Version ac07

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