Newport State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Newport State Park clear sky chart from 2005-11-06 to 2026-01-17.

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	13% 9% 3 7% 5% 4 4 4 5% 7% 38%	127525
	Night	15% 11% 4 9% 5% 4 4 3 5% 6% 34%	124418
Transparency	Day	44% 6% 14% 24% 11% 1	130999
	Night	49% 5% 13% 21% 10% 1	129018
Seeing	Day	16% 9% 28% 29% 15% 3	17618
	Night	19% 9% 28% 29% 13% 2	27578

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	10% 12% 7% 13% 7% 5% 5% 4 5% 7% 26%	3697
	11th to 20th	Day	14% 11% 5% 11% 8% 8% 6% 4 5% 6% 22%	3668
	21st to end	Day	14% 13% 5% 8% 5% 5% 5% 4 5% 7% 29%	3982
February	1st to 10th	Day	10% 10% 3 10% 6% 6% 5% 5% 6% 6% 32%	1677
	11th to 20th	Day	10% 12% 4 7% 5% 6% 5% 5% 6% 7% 34%	1948
	21st to end	Day	12% 11% 3 10% 6% 5% 5% 4 5% 7% 32%	1650
March	1st to 10th	Day	12% 7% 2 6% 4 4 4 3 6% 7% 44%	4480
	11th to 20th	Day	11% 10% 4 10% 5% 5% 4 4 5% 8% 34%	4695
	21st to end	Day	22% 10% 4 9% 4 4 4 3 5% 5% 30%	5893
April	1st to 10th	Day	15% 11% 4 7% 5% 5% 5% 4 6% 7% 31%	2400
	11th to 20th	Day	18% 8% 3 7% 5% 4 4 3 6% 7% 36%	2412
	21st to end	Day	16% 8% 3 7% 5% 4 4 4 6% 8% 37%	2600
May	1st to 10th	Day	12% 6% 3 5% 4 4 4 3 5% 7% 47%	5903
	11th to 20th	Day	10% 9% 3 7% 5% 5% 4 4 5% 6% 42%	6319
	21st to end	Day	12% 7% 3 6% 4 4 4 3 5% 7% 44%	6935
June	1st to 10th	Day	11% 5% 2 6% 5% 4 4 4 7% 7% 45%	2800
	11th to 20th	Day	12% 6% 2 6% 4 5% 5% 4 5% 9% 42%	2800
	21st to end	Day	11% 6% 2 6% 4 4 5% 4 6% 9% 44%	2800
July	1st to 10th	Day	12% 5% 2 5% 3 4 4 3 6% 11% 45%	6360
	11th to 20th	Day	7% 4 1 4 4 4 4 4 6% 9% 54%	6360
	21st to end	Day	8% 5% 2 5% 3 4 4 4 6% 9% 49%	6924
August	1st to 10th	Day	7% 5% 2 7% 5% 5% 5% 5% 7% 8% 45%	4544
	11th to 20th	Day	13% 4 2 5% 3 3 4 3 4 7% 52%	4174
	21st to end	Day	12% 5% 2 6% 4 4 4 4 4 7% 47%	4322
September	1st to 10th	Day	12% 7% 2 6% 4 4 5% 4 6% 8% 44%	2400
	11th to 20th	Day	12% 5% 2 5% 4 4 4 4 6% 8% 46%	2240
	21st to end	Day	14% 6% 2 7% 4 5% 4 4 6% 9% 39%	2200
October	1st to 10th	Day	16% 8% 3 5% 4 4 4 4 4 7% 41%	2175
	11th to 20th	Day	22% 12% 3 7% 5% 4 5% 3 5% 5% 28%	1880
	21st to end	Day	20% 12% 3 8% 6% 5% 5% 4 5% 5% 27%	1980
November	1st to 10th	Day	15% 12% 3 7% 6% 4 4 3 5% 7% 33%	1852
	11th to 20th	Day	15% 16% 5% 10% 6% 5% 5% 4 5% 6% 22%	1890
	21st to end	Day	19% 15% 6% 11% 5% 5% 4 3 5% 6% 21%	1717
December	1st to 10th	Day	13% 18% 8% 13% 6% 6% 6% 4 5% 5% 17%	2690
	11th to 20th	Day	16% 17% 6% 14% 8% 8% 6% 3 4 5% 14%	3088
	21st to end	Day	21% 20% 7% 15% 5% 5% 4 2 3 4 14%	4070
January	1st to 10th	Night	11% 13% 5% 16% 6% 5% 5% 3 4 7% 24%	6488
	11th to 20th	Night	11% 16% 5% 14% 9% 7% 7% 4 4 5% 18%	6445
	21st to end	Night	10% 13% 6% 9% 5% 5% 5% 4 5% 7% 32%	6996
February	1st to 10th	Night	11% 13% 5% 10% 6% 5% 5% 4 5% 6% 29%	2718
	11th to 20th	Night	11% 12% 4 10% 6% 4 4 4 6% 6% 33%	2338
	21st to end	Night	15% 11% 4 8% 6% 5% 5% 4 6% 6% 30%	1980
March	1st to 10th	Night	15% 9% 3 6% 4 3 3 2 4 7% 44%	5373
	11th to 20th	Night	11% 10% 4 8% 5% 4 5% 4 6% 9% 35%	5264
	21st to end	Night	21% 9% 2 8% 5% 4 5% 4 5% 6% 31%	5064
April	1st to 10th	Night	18% 12% 4 9% 5% 4 4 3 5% 6% 32%	2000
	11th to 20th	Night	20% 8% 3 6% 5% 3 4 3 4 5% 36%	1936
	21st to end	Night	16% 9% 3 8% 6% 4 3 3 5% 6% 37%	1800
May	1st to 10th	Night	14% 7% 2 6% 4 3 3 3 5% 7% 45%	3991
	11th to 20th	Night	11% 8% 3 8% 4 5% 5% 4 5% 6% 39%	3596
	21st to end	Night	18% 7% 3 5% 4 4 4 3 5% 6% 41%	3942
June	1st to 10th	Night	13% 6% 2 6% 4 5% 4 5% 7% 7% 43%	1600
	11th to 20th	Night	14% 7% 3 7% 5% 4 5% 4 6% 7% 38%	1600
	21st to end	Night	13% 7% 2 5% 4 4 4 4 6% 8% 44%	1600
July	1st to 10th	Night	12% 4 2 6% 4 4 4 4 6% 7% 45%	3618
	11th to 20th	Night	9% 5% 1 5% 4 3 3 3 4 7% 55%	3617
	21st to end	Night	8% 4 2 6% 4 4 4 4 5% 8% 52%	3947
August	1st to 10th	Night	11% 5% 2 7% 4 4 5% 4 5% 8% 45%	2614
	11th to 20th	Night	12% 4 2 4 3 3 4 3 6% 8% 50%	2875
	21st to end	Night	11% 6% 2 7% 4 5% 3 3 4 6% 49%	3573
September	1st to 10th	Night	11% 5% 2 5% 4 3 3 3 5% 7% 50%	2000
	11th to 20th	Night	13% 5% 2 6% 3 3 3 4 4 7% 48%	2139
	21st to end	Night	15% 7% 2 7% 4 4 4 3 5% 7% 42%	2200
October	1st to 10th	Night	17% 8% 2 6% 4 4 3 4 5% 7% 40%	2221
	11th to 20th	Night	21% 10% 2 8% 4 4 4 3 5% 6% 32%	2520
	21st to end	Night	23% 12% 3 7% 5% 4 4 3 5% 6% 28%	2860
November	1st to 10th	Night	15% 13% 3 7% 4 4 4 3 6% 7% 33%	2666
	11th to 20th	Night	17% 16% 5% 11% 5% 5% 4 3 4 5% 26%	2730
	21st to end	Night	19% 17% 6% 9% 5% 4 5% 4 4 6% 21%	2898
December	1st to 10th	Night	16% 14% 8% 11% 5% 4 4 3 5% 7% 24%	4720
	11th to 20th	Night	16% 17% 7% 15% 6% 8% 4 4 4 5% 15%	5339
	21st to end	Night	25% 18% 6% 12% 4 4 3 3 4 4 16%	7150

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	57% 5% 15% 17% 5%	3698
	11th to 20th	Day	57% 8% 11% 16% 6% 1	3668
	21st to end	Day	55% 5% 14% 15% 11% 1	3982
February	1st to 10th	Day	49% 7% 16% 22% 6%	1677
	11th to 20th	Day	48% 8% 15% 19% 10% 1	1958
	21st to end	Day	50% 7% 13% 19% 9% 1	1650
March	1st to 10th	Day	38% 5% 17% 20% 16% 3	4480
	11th to 20th	Day	47% 6% 16% 21% 9% 1	4695
	21st to end	Day	56% 6% 10% 18% 9%	5895
April	1st to 10th	Day	52% 5% 13% 20% 10% 1	2400
	11th to 20th	Day	47% 5% 10% 25% 12% 2	2412
	21st to end	Day	45% 7% 11% 20% 16% 2	2600
May	1st to 10th	Day	36% 6% 12% 27% 17% 2	5938
	11th to 20th	Day	40% 6% 11% 26% 15% 2	6323
	21st to end	Day	38% 6% 10% 24% 18% 3	6949
June	1st to 10th	Day	35% 6% 15% 29% 14% 2	2800
	11th to 20th	Day	39% 7% 14% 24% 15% 1	2800
	21st to end	Day	37% 8% 17% 24% 13% 1	2800
July	1st to 10th	Day	33% 7% 15% 32% 11% 1	6291
	11th to 20th	Day	26% 6% 14% 40% 12% 1	6285
	21st to end	Day	31% 6% 15% 30% 17% 1	6728
August	1st to 10th	Day	34% 8% 16% 28% 12% 1	4529
	11th to 20th	Day	33% 6% 17% 32% 12%	4213
	21st to end	Day	37% 6% 16% 28% 12% 1	4321
September	1st to 10th	Day	37% 8% 15% 27% 12% 1	2400
	11th to 20th	Day	34% 7% 21% 29% 8%	2240
	21st to end	Day	41% 7% 16% 26% 10%	2200
October	1st to 10th	Day	29% 4 13% 33% 19% 1	3539
	11th to 20th	Day	52% 4 11% 23% 9%	3044
	21st to end	Day	52% 5% 15% 21% 6%	3180
November	1st to 10th	Day	50% 6% 14% 19% 10% 1	1852
	11th to 20th	Day	62% 5% 15% 13% 5%	1890
	21st to end	Day	63% 7% 15% 13% 2	1717
December	1st to 10th	Day	66% 7% 13% 11% 2	2690
	11th to 20th	Day	71% 5% 10% 9% 4	3085
	21st to end	Day	75% 4 7% 11% 3	4070
January	1st to 10th	Night	58% 5% 11% 22% 4	6488
	11th to 20th	Night	63% 5% 14% 10% 7%	6445
	21st to end	Night	52% 4 16% 20% 8%	6996
February	1st to 10th	Night	54% 5% 11% 21% 8% 1	2718
	11th to 20th	Night	50% 6% 12% 21% 9% 2	2339
	21st to end	Night	52% 5% 15% 20% 8% 1	1980
March	1st to 10th	Night	42% 4 17% 24% 13% 1	5373
	11th to 20th	Night	45% 5% 19% 20% 11% 1	5264
	21st to end	Night	52% 6% 12% 20% 9% 1	5064
April	1st to 10th	Night	53% 5% 9% 18% 13% 2	2000
	11th to 20th	Night	48% 5% 10% 21% 13% 3	1936
	21st to end	Night	49% 5% 11% 20% 14% 3	1800
May	1st to 10th	Night	38% 5% 12% 24% 16% 3	4018
	11th to 20th	Night	42% 6% 10% 24% 15% 2	3597
	21st to end	Night	44% 5% 10% 24% 11% 6%	3950
June	1st to 10th	Night	37% 7% 10% 29% 15% 2	1600
	11th to 20th	Night	41% 8% 13% 20% 17% 2	1600
	21st to end	Night	37% 6% 16% 25% 14% 2	1600
July	1st to 10th	Night	37% 6% 14% 28% 13% 3	3580
	11th to 20th	Night	28% 5% 14% 36% 15% 2	3572
	21st to end	Night	30% 5% 15% 27% 22% 1	3832
August	1st to 10th	Night	36% 7% 14% 27% 15% 1	2605
	11th to 20th	Night	32% 6% 16% 31% 14% 1	2902
	21st to end	Night	37% 5% 14% 25% 17% 2	3573
September	1st to 10th	Night	34% 6% 14% 29% 16% 2	2000
	11th to 20th	Night	36% 5% 14% 32% 12% 1	2139
	21st to end	Night	42% 5% 15% 24% 12% 1	2200
October	1st to 10th	Night	37% 4 10% 35% 13% 1	3637
	11th to 20th	Night	44% 5% 14% 24% 14%	4095
	21st to end	Night	51% 4 13% 22% 9%	4610
November	1st to 10th	Night	49% 6% 13% 22% 9% 1	2666
	11th to 20th	Night	60% 6% 12% 13% 8% 1	2730
	21st to end	Night	63% 5% 15% 14% 2 1	2898
December	1st to 10th	Night	59% 6% 18% 14% 2	4720
	11th to 20th	Night	70% 5% 11% 11% 3	5341
	21st to end	Night	71% 4 9% 10% 5%	7150

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	14% 15% 38% 24% 9%	330
	11th to 20th	Day	19% 15% 38% 22% 5% 1	318
	21st to end	Day	22% 10% 31% 31% 6%	330
February	1st to 10th	Day	13% 15% 44% 20% 7% 2	300
	11th to 20th	Day	14% 18% 42% 20% 5%	300
	21st to end	Day	17% 12% 49% 18% 4	249
March	1st to 10th	Day	14% 11% 45% 24% 6%	300
	11th to 20th	Day	14% 15% 34% 27% 9% 2	371
	21st to end	Day	22% 13% 30% 27% 8% 1	550
April	1st to 10th	Day	19% 14% 32% 26% 8% 2	500
	11th to 20th	Day	19% 13% 31% 24% 10% 3	492
	21st to end	Day	18% 10% 30% 28% 12% 2	500
May	1st to 10th	Day	16% 10% 33% 27% 11% 2	518
	11th to 20th	Day	15% 6% 28% 35% 15% 2	725
	21st to end	Day	15% 6% 26% 32% 17% 4	789
June	1st to 10th	Day	11% 5% 30% 35% 15% 3	730
	11th to 20th	Day	16% 4 25% 36% 15% 2	730
	21st to end	Day	13% 5% 25% 36% 18% 3	730
July	1st to 10th	Day	9% 2 17% 40% 26% 5%	721
	11th to 20th	Day	9% 4 23% 36% 23% 6%	718
	21st to end	Day	7% 3 20% 38% 26% 6%	794
August	1st to 10th	Day	7% 3 19% 37% 27% 7%	720
	11th to 20th	Day	13% 3 16% 31% 28% 8%	519
	21st to end	Day	15% 5% 18% 30% 25% 7%	583
September	1st to 10th	Day	15% 9% 20% 31% 17% 8%	530
	11th to 20th	Day	11% 5% 19% 34% 24% 7%	530
	21st to end	Day	17% 8% 21% 29% 19% 6%	530
October	1st to 10th	Day	19% 11% 29% 26% 13% 3	505
	11th to 20th	Day	22% 13% 34% 25% 6%	330
	21st to end	Day	26% 13% 32% 20% 8%	363
November	1st to 10th	Day	16% 14% 36% 27% 7%	330
	11th to 20th	Day	18% 21% 37% 20% 4	330
	21st to end	Day	24% 19% 36% 18% 3	330
December	1st to 10th	Day	21% 18% 38% 17% 7% 1	330
	11th to 20th	Day	24% 21% 37% 15% 3 1	330
	21st to end	Day	31% 17% 31% 17% 4 1	363
January	1st to 10th	Night	18% 13% 37% 25% 6%	1050
	11th to 20th	Night	20% 14% 35% 24% 7%	1031
	21st to end	Night	18% 9% 36% 28% 8% 1	1100
February	1st to 10th	Night	17% 11% 38% 26% 7% 1	993
	11th to 20th	Night	17% 13% 36% 26% 8%	783
	21st to end	Night	19% 12% 37% 28% 4	660
March	1st to 10th	Night	17% 8% 36% 29% 9% 1	800
	11th to 20th	Night	15% 10% 37% 30% 7% 1	800
	21st to end	Night	20% 8% 30% 32% 10% 1	710
April	1st to 10th	Night	22% 8% 32% 30% 6% 2	600
	11th to 20th	Night	23% 6% 28% 29% 13% 1	593
	21st to end	Night	18% 6% 30% 34% 11% 1	600
May	1st to 10th	Night	20% 5% 28% 33% 14% 1	600
	11th to 20th	Night	17% 4 26% 37% 14% 2	591
	21st to end	Night	13% 4 20% 39% 22% 3	650
June	1st to 10th	Night	14% 2 26% 36% 21% 1	600
	11th to 20th	Night	16% 3 21% 37% 20% 3	600
	21st to end	Night	15% 3 20% 36% 24% 2	600
July	1st to 10th	Night	9% 2 14% 42% 30% 3	585
	11th to 20th	Night	11% 2 17% 35% 31% 4	582
	21st to end	Night	9% 2 18% 40% 26% 4	657
August	1st to 10th	Night	10% 1 14% 39% 31% 5%	597
	11th to 20th	Night	10% 2 16% 34% 31% 7%	594
	21st to end	Night	12% 4 18% 37% 28% 2	660
September	1st to 10th	Night	13% 5% 20% 33% 22% 8%	600
	11th to 20th	Night	14% 5% 18% 32% 23% 7%	739
	21st to end	Night	17% 8% 20% 30% 21% 5%	800
October	1st to 10th	Night	20% 9% 25% 26% 18% 2	800
	11th to 20th	Night	26% 11% 28% 24% 10% 1	800
	21st to end	Night	29% 12% 24% 26% 8% 1	880
November	1st to 10th	Night	24% 13% 31% 26% 6%	820
	11th to 20th	Night	24% 18% 32% 20% 6% 1	840
	21st to end	Night	26% 16% 29% 22% 6%	1008
December	1st to 10th	Night	25% 17% 33% 20% 6%	1050
	11th to 20th	Night	23% 16% 35% 17% 7% 1	1050
	21st to end	Night	28% 13% 34% 21% 3	1155

Page generated at 2026-01-14 00:14:30. Version ac07

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