Caumsett State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Caumsett State Park clear sky chart from 2005-11-06 to 2024-01-17.

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 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	15% 6% 2 5% 5% 3 4 5% 5% 8% 42%	74805
	Night	16% 7% 3 5% 5% 3 4 4 5% 7% 42%	75005
Transparency	Day	41% 6% 12% 23% 16% 2	74510
	Night	42% 5% 11% 23% 16% 2	74834
Seeing	Day	18% 11% 29% 27% 13% 2	13912
	Night	19% 11% 31% 28% 9% 1	23135

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	14% 6% 2 5% 5% 3 4 4 6% 8% 43%	1517
	11th to 20th	Day	16% 9% 2 4 5% 3 4 6% 6% 7% 37%	1488
	21st to end	Day	14% 7% 3 5% 4 3 5% 4 6% 7% 41%	1683
February	1st to 10th	Day	18% 6% 4 6% 5% 3 4 5% 4 7% 39%	1661
	11th to 20th	Day	15% 4 2 6% 5% 3 4 4 4 7% 44%	1748
	21st to end	Day	20% 7% 2 6% 4 3 4 4 5% 6% 40%	1480
March	1st to 10th	Day	14% 6% 2 5% 5% 3 3 4 5% 8% 44%	1797
	11th to 20th	Day	15% 6% 2 4 5% 3 5% 4 7% 9% 40%	1861
	21st to end	Day	19% 8% 3 5% 4 3 4 4 4 6% 41%	2376
April	1st to 10th	Day	16% 8% 3 5% 5% 3 4 4 6% 7% 41%	2160
	11th to 20th	Day	16% 5% 2 5% 5% 3 3 4 5% 7% 43%	2134
	21st to end	Day	20% 5% 2 4 4 3 5% 4 5% 7% 42%	2214
May	1st to 10th	Day	21% 7% 2 5% 4 2 3 4 6% 7% 38%	2340
	11th to 20th	Day	18% 6% 3 4 5% 3 4 5% 6% 8% 39%	2419
	21st to end	Day	14% 5% 2 4 4 3 4 5% 5% 9% 44%	2725
June	1st to 10th	Day	16% 5% 2 5% 4 3 4 5% 6% 9% 40%	2520
	11th to 20th	Day	13% 6% 3 5% 6% 3 5% 5% 6% 9% 39%	2520
	21st to end	Day	10% 6% 3 5% 5% 3 5% 6% 5% 9% 44%	2520
July	1st to 10th	Day	10% 5% 2 6% 5% 3 5% 7% 6% 8% 43%	2520
	11th to 20th	Day	9% 5% 3 4 5% 3 5% 5% 7% 10% 45%	2520
	21st to end	Day	12% 5% 2 5% 5% 4 5% 5% 6% 9% 40%	2744
August	1st to 10th	Day	9% 5% 2 5% 6% 4 5% 6% 7% 10% 41%	2385
	11th to 20th	Day	11% 5% 2 5% 6% 3 5% 5% 6% 9% 43%	2126
	21st to end	Day	11% 4 3 5% 5% 2 5% 5% 6% 9% 45%	2376
September	1st to 10th	Day	13% 5% 2 5% 4 3 4 4 5% 8% 46%	2160
	11th to 20th	Day	12% 5% 2 3 3 3 4 4 5% 7% 52%	2057
	21st to end	Day	17% 6% 2 6% 5% 2 4 4 4 6% 44%	1980
October	1st to 10th	Day	20% 7% 2 4 3 3 3 4 4 7% 43%	1920
	11th to 20th	Day	14% 6% 2 4 5% 3 4 5% 4 7% 46%	1800
	21st to end	Day	20% 6% 2 5% 5% 3 4 4 5% 6% 40%	1805
November	1st to 10th	Day	14% 6% 2 4 5% 2 3 4 4 6% 50%	1671
	11th to 20th	Day	17% 6% 2 4 3 2 3 4 4 6% 48%	1710
	21st to end	Day	14% 6% 2 5% 4 2 4 5% 5% 6% 45%	1670
December	1st to 10th	Day	17% 7% 3 5% 5% 3 4 5% 6% 7% 37%	1520
	11th to 20th	Day	23% 5% 3 4 3 2 3 3 4 6% 46%	1906
	21st to end	Day	17% 9% 4 7% 6% 3 5% 5% 5% 6% 32%	2772
January	1st to 10th	Night	16% 6% 3 5% 4 2 4 3 5% 6% 46%	2649
	11th to 20th	Night	19% 7% 3 5% 5% 3 4 4 6% 6% 39%	2611
	21st to end	Night	14% 9% 3 4 4 2 3 4 5% 8% 44%	2670
February	1st to 10th	Night	17% 9% 3 5% 4 3 4 4 4 6% 40%	2297
	11th to 20th	Night	18% 8% 3 5% 5% 3 4 4 4 7% 39%	2098
	21st to end	Night	20% 6% 2 4 4 3 4 5% 4 5% 42%	1776
March	1st to 10th	Night	16% 6% 2 4 4 2 4 5% 4 7% 45%	2150
	11th to 20th	Night	16% 6% 2 5% 6% 3 4 4 6% 7% 41%	2094
	21st to end	Night	18% 8% 3 5% 5% 2 4 3 5% 7% 40%	1980
April	1st to 10th	Night	18% 8% 3 5% 4 4 4 5% 5% 6% 39%	1800
	11th to 20th	Night	18% 7% 2 5% 5% 3 3 4 4 7% 41%	1775
	21st to end	Night	19% 7% 3 6% 5% 2 3 3 4 6% 42%	1744
May	1st to 10th	Night	21% 8% 3 6% 6% 3 4 4 5% 7% 34%	1620
	11th to 20th	Night	19% 8% 3 5% 5% 3 4 4 5% 6% 38%	1488
	21st to end	Night	16% 7% 2 5% 5% 2 5% 5% 5% 7% 40%	1550
June	1st to 10th	Night	17% 6% 3 6% 5% 2 4 5% 5% 7% 40%	1440
	11th to 20th	Night	14% 6% 3 5% 4 2 5% 4 7% 8% 40%	1440
	21st to end	Night	10% 4 2 5% 5% 3 6% 6% 7% 10% 42%	1440
July	1st to 10th	Night	11% 6% 3 6% 7% 3 5% 6% 6% 9% 39%	1440
	11th to 20th	Night	11% 6% 3 5% 4 5% 5% 6% 7% 9% 39%	1440
	21st to end	Night	10% 6% 3 5% 5% 3 5% 4 7% 11% 41%	1574
August	1st to 10th	Night	7% 5% 2 5% 6% 4 4 5% 8% 9% 44%	1530
	11th to 20th	Night	11% 6% 3 6% 6% 4 6% 6% 7% 9% 37%	1774
	21st to end	Night	13% 5% 2 5% 4 4 5% 4 6% 8% 44%	1980
September	1st to 10th	Night	14% 4 2 6% 5% 3 4 5% 6% 7% 43%	1800
	11th to 20th	Night	13% 6% 3 4 5% 2 3 3 4 6% 51%	1901
	21st to end	Night	17% 5% 2 5% 6% 2 3 4 4 6% 44%	1980
October	1st to 10th	Night	19% 8% 3 5% 5% 3 3 3 4 6% 41%	2038
	11th to 20th	Night	15% 5% 2 4 4 3 4 4 4 7% 48%	2160
	21st to end	Night	22% 7% 3 5% 4 2 4 4 4 6% 41%	2549
November	1st to 10th	Night	13% 5% 2 5% 5% 3 4 4 5% 6% 49%	2407
	11th to 20th	Night	19% 6% 2 4 3 2 3 3 4 5% 48%	2470
	21st to end	Night	14% 5% 2 4 5% 3 4 4 5% 7% 47%	2508
December	1st to 10th	Night	20% 6% 3 5% 5% 3 4 4 6% 6% 39%	2660
	11th to 20th	Night	20% 6% 2 5% 4 3 3 4 5% 6% 42%	3288
	21st to end	Night	20% 9% 3 5% 4 3 4 5% 5% 5% 37%	4884

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	40% 5% 11% 28% 12% 4	1518
	11th to 20th	Day	45% 5% 13% 23% 12% 2	1488
	21st to end	Day	43% 5% 10% 25% 15% 2	1683
February	1st to 10th	Day	46% 5% 12% 22% 13% 1	1661
	11th to 20th	Day	42% 4 10% 25% 16% 2	1757
	21st to end	Day	48% 4 10% 21% 14% 3	1480
March	1st to 10th	Day	40% 5% 13% 23% 16% 3	1800
	11th to 20th	Day	41% 5% 13% 24% 15% 2	1861
	21st to end	Day	47% 5% 7% 19% 17% 5%	2376
April	1st to 10th	Day	43% 6% 9% 22% 16% 4	2160
	11th to 20th	Day	41% 6% 10% 23% 18% 3	2134
	21st to end	Day	42% 6% 10% 21% 17% 4	2214
May	1st to 10th	Day	47% 6% 9% 20% 15% 2	2340
	11th to 20th	Day	42% 7% 12% 21% 16% 3	2423
	21st to end	Day	37% 8% 18% 21% 13% 2	2725
June	1st to 10th	Day	41% 7% 13% 23% 15% 1	2520
	11th to 20th	Day	43% 7% 13% 23% 13% 2	2520
	21st to end	Day	38% 8% 15% 24% 15% 1	2520
July	1st to 10th	Day	37% 9% 13% 22% 17% 1	2450
	11th to 20th	Day	35% 7% 16% 26% 14% 2	2445
	21st to end	Day	39% 8% 13% 21% 17% 2	2591
August	1st to 10th	Day	36% 9% 16% 25% 14% 1	2371
	11th to 20th	Day	38% 7% 15% 24% 14% 1	2126
	21st to end	Day	36% 7% 13% 22% 19% 2	2376
September	1st to 10th	Day	38% 7% 14% 22% 18% 2	2160
	11th to 20th	Day	33% 5% 12% 25% 24% 2	2057
	21st to end	Day	42% 6% 9% 20% 20% 3	1980
October	1st to 10th	Day	43% 6% 9% 22% 17% 2	1920
	11th to 20th	Day	38% 5% 12% 25% 18% 2	1800
	21st to end	Day	45% 5% 10% 21% 17% 2	1805
November	1st to 10th	Day	37% 4 13% 23% 21% 2	1671
	11th to 20th	Day	39% 3 10% 23% 21% 3	1710
	21st to end	Day	39% 5% 13% 28% 12% 2	1670
December	1st to 10th	Day	45% 5% 15% 20% 14% 1	1520
	11th to 20th	Day	42% 4 14% 22% 16% 2	1906
	21st to end	Day	51% 6% 11% 23% 9%	2772
January	1st to 10th	Night	41% 3 11% 25% 16% 4	2649
	11th to 20th	Night	45% 6% 13% 23% 10% 2	2611
	21st to end	Night	40% 3 10% 25% 20% 2	2670
February	1st to 10th	Night	45% 4 12% 23% 12% 2	2297
	11th to 20th	Night	45% 5% 10% 21% 15% 5%	2100
	21st to end	Night	44% 4 7% 25% 17% 4	1776
March	1st to 10th	Night	40% 4 12% 24% 16% 4	2160
	11th to 20th	Night	43% 4 9% 22% 16% 4	2095
	21st to end	Night	44% 4 8% 19% 18% 5%	1980
April	1st to 10th	Night	46% 5% 9% 18% 18% 3	1800
	11th to 20th	Night	44% 5% 10% 18% 21% 1	1775
	21st to end	Night	45% 5% 8% 21% 16% 5%	1744
May	1st to 10th	Night	50% 6% 10% 17% 15% 2	1620
	11th to 20th	Night	49% 6% 9% 18% 16% 2	1489
	21st to end	Night	43% 8% 15% 21% 12% 2	1551
June	1st to 10th	Night	43% 6% 10% 21% 18% 1	1440
	11th to 20th	Night	40% 7% 15% 25% 12% 1	1440
	21st to end	Night	36% 9% 13% 27% 13% 1	1440
July	1st to 10th	Night	40% 9% 15% 20% 14% 2	1400
	11th to 20th	Night	39% 8% 13% 26% 12% 1	1392
	21st to end	Night	34% 9% 17% 23% 14% 2	1486
August	1st to 10th	Night	34% 7% 18% 24% 15% 1	1520
	11th to 20th	Night	41% 8% 15% 24% 10% 1	1774
	21st to end	Night	37% 7% 14% 22% 19% 2	1980
September	1st to 10th	Night	40% 6% 11% 25% 16% 1	1800
	11th to 20th	Night	34% 5% 10% 24% 22% 3	1901
	21st to end	Night	42% 6% 7% 21% 21% 3	1980
October	1st to 10th	Night	46% 5% 10% 22% 14% 3	2038
	11th to 20th	Night	36% 4 13% 29% 15% 1	2160
	21st to end	Night	45% 4 11% 22% 17% 1	2549
November	1st to 10th	Night	38% 5% 10% 23% 20% 4	2407
	11th to 20th	Night	40% 4 8% 25% 19% 4	2470
	21st to end	Night	37% 4 13% 30% 14% 2	2508
December	1st to 10th	Night	46% 5% 13% 22% 14% 1	2660
	11th to 20th	Night	44% 4 12% 20% 18% 2	3288
	21st to end	Night	48% 5% 10% 25% 11% 1	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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	22% 21% 34% 19% 4	180
	11th to 20th	Day	16% 28% 34% 18% 3	172
	21st to end	Day	18% 16% 43% 18% 5% 1	220
February	1st to 10th	Day	27% 14% 41% 17% 1	281
	11th to 20th	Day	19% 19% 42% 19% 2	416
	21st to end	Day	25% 19% 34% 17% 5%	346
March	1st to 10th	Day	12% 21% 40% 22% 4	420
	11th to 20th	Day	18% 14% 41% 23% 4 1	420
	21st to end	Day	23% 16% 35% 18% 6% 1	462
April	1st to 10th	Day	20% 17% 37% 17% 8% 1	420
	11th to 20th	Day	19% 14% 32% 25% 9% 1	412
	21st to end	Day	26% 12% 34% 22% 5% 1	420
May	1st to 10th	Day	27% 12% 31% 23% 6% 1	423
	11th to 20th	Day	18% 9% 32% 32% 8% 1	447
	21st to end	Day	17% 4 21% 32% 23% 2	485
June	1st to 10th	Day	19% 5% 24% 33% 17% 2	450
	11th to 20th	Day	16% 7% 28% 34% 14% 2	450
	21st to end	Day	12% 3 28% 34% 20% 3	450
July	1st to 10th	Day	11% 3 18% 38% 24% 5%	445
	11th to 20th	Day	9% 3 18% 37% 26% 5%	444
	21st to end	Day	13% 4 19% 41% 20% 3	488
August	1st to 10th	Day	11% 5% 18% 38% 24% 6%	446
	11th to 20th	Day	14% 3 17% 38% 26% 3	439
	21st to end	Day	12% 4 22% 36% 19% 7%	495
September	1st to 10th	Day	17% 4 24% 26% 22% 7%	450
	11th to 20th	Day	15% 4 22% 28% 22% 9%	450
	21st to end	Day	21% 6% 27% 28% 15% 4	450
October	1st to 10th	Day	26% 7% 23% 24% 16% 4	450
	11th to 20th	Day	15% 12% 29% 28% 14% 2	450
	21st to end	Day	22% 13% 32% 23% 9% 1	408
November	1st to 10th	Day	15% 12% 27% 32% 11% 2	365
	11th to 20th	Day	20% 19% 31% 23% 6% 1	370
	21st to end	Day	17% 17% 33% 25% 7% 1	330
December	1st to 10th	Day	18% 17% 39% 19% 6% 1	180
	11th to 20th	Day	26% 24% 30% 17% 3	180
	21st to end	Day	22% 21% 36% 14% 7% 1	198
January	1st to 10th	Night	19% 19% 39% 20% 4	760
	11th to 20th	Night	24% 17% 33% 24% 2	747
	21st to end	Night	18% 17% 41% 21% 2	792
February	1st to 10th	Night	21% 15% 40% 22% 2	720
	11th to 20th	Night	23% 19% 38% 19% 2	703
	21st to end	Night	23% 19% 36% 19% 4	592
March	1st to 10th	Night	21% 16% 38% 21% 5%	720
	11th to 20th	Night	21% 13% 41% 21% 4 1	720
	21st to end	Night	21% 14% 40% 21% 5%	792
April	1st to 10th	Night	23% 14% 35% 23% 5% 1	720
	11th to 20th	Night	20% 13% 33% 28% 6%	711
	21st to end	Night	22% 10% 35% 27% 6% 1	664
May	1st to 10th	Night	25% 8% 32% 27% 7% 1	540
	11th to 20th	Night	21% 9% 37% 26% 6%	427
	21st to end	Night	20% 6% 19% 39% 14% 2	389
June	1st to 10th	Night	20% 6% 25% 34% 16%	360
	11th to 20th	Night	16% 5% 21% 41% 15%	360
	21st to end	Night	10% 3 22% 52% 13% 1	360
July	1st to 10th	Night	12% 3 23% 42% 18% 1	350
	11th to 20th	Night	11% 5% 18% 43% 20% 3	348
	21st to end	Night	13% 3 21% 46% 17% 1	394
August	1st to 10th	Night	10% 3 21% 46% 19% 1	456
	11th to 20th	Night	14% 3 17% 38% 26% 2	710
	21st to end	Night	13% 5% 17% 38% 24% 3	792
September	1st to 10th	Night	16% 3 25% 36% 17% 3	720
	11th to 20th	Night	16% 5% 21% 34% 19% 5%	720
	21st to end	Night	21% 4 23% 32% 18% 2	720
October	1st to 10th	Night	22% 8% 26% 27% 14% 3	720
	11th to 20th	Night	18% 10% 28% 32% 12%	720
	21st to end	Night	24% 10% 34% 24% 7% 1	792
November	1st to 10th	Night	15% 11% 33% 29% 11% 2	740
	11th to 20th	Night	22% 14% 33% 23% 8%	760
	21st to end	Night	16% 16% 35% 25% 6% 1	760
December	1st to 10th	Night	24% 16% 35% 19% 5% 1	760
	11th to 20th	Night	22% 16% 37% 22% 4	760
	21st to end	Night	23% 14% 39% 21% 2	836

Page generated at 2024-01-13 23:56:38. Version ac07

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