Hawn State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hawn State Park clear sky chart from 2005-11-06 to 2024-01-31.

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	12% 6% 3 5% 5% 3 5% 5% 5% 8% 43%	74904
	Night	12% 7% 3 5% 5% 3 4 4 5% 7% 46%	75245
Transparency	Day	39% 6% 12% 24% 16% 3	74614
	Night	39% 5% 11% 24% 18% 3	75056
Seeing	Day	16% 13% 28% 24% 14% 4	14453
	Night	17% 14% 30% 26% 12% 2	24426

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	13% 9% 4 7% 5% 3 5% 4 4 6% 39%	1517
	11th to 20th	Day	15% 10% 3 6% 6% 3 4 4 4 6% 38%	1665
	21st to end	Day	12% 10% 4 7% 6% 3 4 4 5% 5% 41%	1872
February	1st to 10th	Day	16% 10% 4 6% 5% 3 4 4 5% 5% 38%	1638
	11th to 20th	Day	14% 8% 4 7% 4 3 5% 5% 6% 7% 36%	1748
	21st to end	Day	14% 10% 4 6% 5% 3 6% 4 5% 7% 38%	1480
March	1st to 10th	Day	14% 8% 4 6% 5% 2 4 4 4 6% 44%	1814
	11th to 20th	Day	19% 9% 4 6% 6% 3 4 5% 4 5% 36%	1980
	21st to end	Day	19% 10% 4 7% 5% 4 5% 5% 6% 5% 30%	2299
April	1st to 10th	Day	10% 4 3 5% 6% 3 4 5% 6% 9% 46%	2160
	11th to 20th	Day	16% 8% 3 6% 6% 3 4 4 4 7% 40%	2134
	21st to end	Day	19% 6% 3 5% 4 3 5% 4 5% 7% 39%	2160
May	1st to 10th	Day	15% 5% 3 5% 7% 2 5% 5% 5% 8% 38%	2196
	11th to 20th	Day	16% 6% 2 5% 4 3 4 5% 5% 8% 41%	2395
	21st to end	Day	9% 6% 3 6% 6% 4 5% 7% 7% 10% 38%	2725
June	1st to 10th	Day	9% 4 2 5% 5% 3 5% 5% 7% 9% 45%	2520
	11th to 20th	Day	6% 3 1 4 5% 3 5% 5% 7% 9% 51%	2520
	21st to end	Day	5% 2 2 3 5% 3 6% 6% 8% 10% 49%	2520
July	1st to 10th	Day	10% 3 2 4 6% 3 6% 6% 7% 10% 41%	2520
	11th to 20th	Day	4 3 2 4 5% 3 7% 6% 7% 10% 48%	2520
	21st to end	Day	7% 5% 3 5% 5% 4 6% 7% 7% 8% 44%	2584
August	1st to 10th	Day	8% 4 2 4 5% 4 6% 6% 7% 11% 43%	2284
	11th to 20th	Day	10% 4 2 6% 5% 3 7% 6% 7% 9% 41%	2125
	21st to end	Day	8% 5% 2 5% 5% 3 5% 5% 6% 9% 47%	2376
September	1st to 10th	Day	12% 5% 2 5% 4 3 3 4 5% 9% 48%	2160
	11th to 20th	Day	10% 4 2 4 5% 3 4 5% 5% 9% 48%	2124
	21st to end	Day	11% 4 1 4 5% 2 3 5% 4 6% 56%	1980
October	1st to 10th	Day	9% 4 2 4 4 2 3 4 4 6% 57%	1818
	11th to 20th	Day	13% 4 2 5% 3 3 4 3 4 6% 53%	1800
	21st to end	Day	18% 7% 2 5% 4 2 3 4 3 5% 47%	1971
November	1st to 10th	Day	10% 5% 2 5% 3 2 4 4 4 6% 55%	1672
	11th to 20th	Day	12% 8% 3 5% 4 2 4 4 5% 8% 46%	1710
	21st to end	Day	15% 8% 3 5% 5% 2 4 4 5% 5% 43%	1696
December	1st to 10th	Day	14% 10% 2 5% 5% 3 4 4 5% 6% 42%	1520
	11th to 20th	Day	13% 10% 3 6% 6% 4 5% 4 5% 6% 38%	1918
	21st to end	Day	17% 12% 5% 6% 6% 3 5% 4 5% 6% 30%	2783
January	1st to 10th	Night	13% 9% 3 6% 5% 3 4 5% 5% 6% 40%	2648
	11th to 20th	Night	16% 9% 4 7% 5% 4 5% 4 4 5% 37%	2513
	21st to end	Night	15% 8% 4 6% 5% 3 4 4 5% 6% 39%	2711
February	1st to 10th	Night	17% 12% 5% 7% 5% 3 4 4 3 5% 35%	2321
	11th to 20th	Night	15% 6% 4 8% 5% 2 4 4 4 5% 42%	2098
	21st to end	Night	16% 8% 4 6% 5% 2 4 5% 5% 5% 39%	1776
March	1st to 10th	Night	16% 8% 3 6% 4 2 4 3 4 5% 43%	2160
	11th to 20th	Night	18% 8% 3 7% 4 3 4 4 5% 5% 39%	1980
	21st to end	Night	18% 9% 3 6% 6% 3 5% 5% 5% 6% 34%	2057
April	1st to 10th	Night	9% 4 3 5% 4 2 5% 5% 5% 7% 51%	1800
	11th to 20th	Night	13% 6% 3 6% 5% 3 5% 5% 5% 6% 45%	1775
	21st to end	Night	18% 6% 3 5% 5% 3 4 4 5% 5% 41%	1800
May	1st to 10th	Night	15% 6% 2 4 4 3 5% 5% 5% 7% 45%	1764
	11th to 20th	Night	14% 6% 3 4 3 2 4 4 6% 7% 46%	1497
	21st to end	Night	8% 5% 3 6% 6% 4 6% 6% 6% 10% 40%	1551
June	1st to 10th	Night	9% 4 2 5% 4 2 5% 5% 6% 8% 49%	1440
	11th to 20th	Night	5% 3 2 3 4 2 3 4 7% 10% 56%	1440
	21st to end	Night	3 2 2 4 3 2 4 5% 7% 10% 57%	1440
July	1st to 10th	Night	8% 3 2 4 4 2 5% 4 6% 9% 53%	1440
	11th to 20th	Night	5% 3 1 4 4 3 4 5% 8% 9% 55%	1440
	21st to end	Night	6% 4 2 4 4 4 5% 6% 7% 10% 49%	1729
August	1st to 10th	Night	7% 4 2 4 4 3 4 5% 7% 9% 52%	1654
	11th to 20th	Night	7% 3 2 5% 5% 3 4 5% 6% 8% 53%	1776
	21st to end	Night	6% 4 2 5% 4 2 4 4 5% 8% 55%	1980
September	1st to 10th	Night	12% 5% 2 4 5% 3 3 4 3 6% 53%	1800
	11th to 20th	Night	8% 5% 2 4 4 2 5% 4 4 8% 53%	1816
	21st to end	Night	9% 4 2 4 4 2 4 4 5% 6% 56%	1980
October	1st to 10th	Night	7% 3 1 4 4 2 4 4 4 7% 62%	2137
	11th to 20th	Night	14% 5% 2 4 3 2 3 3 4 6% 54%	2160
	21st to end	Night	18% 6% 2 5% 4 2 3 3 4 5% 47%	2384
November	1st to 10th	Night	10% 5% 2 4 3 2 3 3 4 6% 59%	2406
	11th to 20th	Night	12% 6% 2 4 4 3 4 4 4 7% 51%	2470
	21st to end	Night	17% 8% 2 4 4 2 4 3 4 5% 46%	2479
December	1st to 10th	Night	16% 9% 3 5% 5% 2 4 4 5% 7% 40%	2660
	11th to 20th	Night	14% 8% 3 6% 5% 3 4 5% 4 5% 42%	3279
	21st to end	Night	14% 15% 4 8% 7% 3 5% 5% 5% 5% 28%	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	46% 6% 10% 22% 13% 3	1518
	11th to 20th	Day	47% 5% 9% 26% 11% 1	1665
	21st to end	Day	45% 4 13% 22% 13% 2	1872
February	1st to 10th	Day	49% 4 12% 22% 13% 1	1638
	11th to 20th	Day	46% 5% 13% 19% 13% 4	1758
	21st to end	Day	47% 4 10% 23% 12% 5%	1480
March	1st to 10th	Day	42% 5% 9% 23% 17% 4	1814
	11th to 20th	Day	51% 5% 9% 18% 14% 3	1980
	21st to end	Day	54% 6% 11% 17% 10% 1	2299
April	1st to 10th	Day	35% 6% 12% 26% 19% 1	2160
	11th to 20th	Day	45% 4 9% 22% 15% 4	2134
	21st to end	Day	45% 6% 11% 23% 13% 1	2160
May	1st to 10th	Day	44% 7% 13% 24% 11% 1	2196
	11th to 20th	Day	41% 7% 13% 23% 15% 1	2399
	21st to end	Day	39% 10% 14% 22% 13% 2	2725
June	1st to 10th	Day	33% 8% 14% 25% 18% 1	2520
	11th to 20th	Day	28% 7% 12% 27% 22% 4	2520
	21st to end	Day	27% 8% 18% 26% 16% 5%	2520
July	1st to 10th	Day	35% 8% 15% 24% 14% 4	2451
	11th to 20th	Day	27% 8% 16% 28% 17% 3	2445
	21st to end	Day	34% 9% 14% 28% 14% 2	2440
August	1st to 10th	Day	32% 9% 16% 29% 14% 1	2270
	11th to 20th	Day	37% 8% 14% 27% 13% 1	2125
	21st to end	Day	32% 7% 16% 23% 17% 5%	2376
September	1st to 10th	Day	34% 5% 12% 30% 15% 4	2160
	11th to 20th	Day	33% 6% 10% 26% 23% 2	2124
	21st to end	Day	29% 6% 8% 29% 26% 3	1980
October	1st to 10th	Day	29% 5% 9% 28% 25% 4	1818
	11th to 20th	Day	33% 4 8% 27% 23% 6%	1800
	21st to end	Day	41% 4 7% 27% 17% 5%	1971
November	1st to 10th	Day	32% 5% 10% 26% 21% 7%	1672
	11th to 20th	Day	36% 5% 9% 24% 21% 6%	1710
	21st to end	Day	43% 5% 9% 24% 17% 1	1696
December	1st to 10th	Day	42% 6% 10% 27% 14% 2	1520
	11th to 20th	Day	47% 4 9% 22% 17% 2	1915
	21st to end	Day	55% 7% 10% 16% 10% 3	2783
January	1st to 10th	Night	44% 5% 9% 23% 17% 2	2648
	11th to 20th	Night	49% 5% 9% 23% 13% 1	2513
	21st to end	Night	46% 4 11% 23% 14% 2	2711
February	1st to 10th	Night	52% 5% 8% 21% 12% 2	2321
	11th to 20th	Night	45% 5% 10% 20% 17% 3	2099
	21st to end	Night	46% 5% 10% 22% 13% 4	1776
March	1st to 10th	Night	45% 4 9% 20% 18% 5%	2160
	11th to 20th	Night	48% 5% 11% 20% 13% 3	1980
	21st to end	Night	51% 5% 13% 21% 9% 1	2057
April	1st to 10th	Night	32% 5% 13% 28% 20% 3	1800
	11th to 20th	Night	40% 5% 11% 22% 18% 4	1775
	21st to end	Night	45% 4 8% 24% 16% 2	1800
May	1st to 10th	Night	39% 6% 13% 24% 16% 2	1764
	11th to 20th	Night	38% 6% 14% 23% 17% 2	1498
	21st to end	Night	38% 9% 14% 20% 16% 3	1552
June	1st to 10th	Night	32% 6% 16% 25% 20% 2	1440
	11th to 20th	Night	23% 5% 13% 32% 23% 5%	1440
	21st to end	Night	20% 8% 18% 30% 17% 7%	1440
July	1st to 10th	Night	28% 6% 16% 28% 16% 5%	1400
	11th to 20th	Night	24% 7% 16% 28% 20% 4	1392
	21st to end	Night	27% 8% 16% 30% 17% 1	1633
August	1st to 10th	Night	27% 7% 18% 31% 15% 2	1644
	11th to 20th	Night	28% 7% 15% 26% 22% 2	1776
	21st to end	Night	26% 7% 13% 27% 22% 5%	1980
September	1st to 10th	Night	33% 4 8% 30% 18% 7%	1800
	11th to 20th	Night	30% 5% 8% 29% 24% 3	1816
	21st to end	Night	29% 5% 9% 25% 27% 5%	1980
October	1st to 10th	Night	24% 5% 11% 27% 28% 5%	2137
	11th to 20th	Night	32% 3 8% 26% 23% 7%	2160
	21st to end	Night	40% 4 9% 23% 20% 5%	2384
November	1st to 10th	Night	28% 4 12% 27% 23% 6%	2406
	11th to 20th	Night	35% 4 8% 23% 23% 6%	2470
	21st to end	Night	41% 5% 8% 24% 20% 2	2479
December	1st to 10th	Night	44% 5% 11% 23% 15% 2	2660
	11th to 20th	Night	44% 5% 9% 24% 17% 1	3281
	21st to end	Night	55% 7% 10% 16% 10% 2	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	30% 22% 32% 13% 3	270
	11th to 20th	Day	29% 30% 31% 9% 1	270
	21st to end	Day	19% 37% 32% 10% 2	294
February	1st to 10th	Day	27% 29% 33% 10% 1	240
	11th to 20th	Day	33% 28% 28% 9% 1 1	240
	21st to end	Day	30% 28% 33% 8% 1	198
March	1st to 10th	Day	25% 24% 39% 10% 1	240
	11th to 20th	Day	32% 23% 33% 9% 2	240
	21st to end	Day	32% 20% 33% 13% 2	385
April	1st to 10th	Day	17% 23% 36% 19% 5%	420
	11th to 20th	Day	26% 20% 26% 20% 6% 1	412
	21st to end	Day	23% 19% 35% 17% 5% 1	420
May	1st to 10th	Day	17% 22% 35% 19% 6% 1	423
	11th to 20th	Day	21% 12% 32% 23% 10% 3	541
	21st to end	Day	10% 8% 36% 27% 15% 5%	679
June	1st to 10th	Day	11% 6% 23% 29% 24% 6%	630
	11th to 20th	Day	6% 5% 30% 34% 19% 5%	630
	21st to end	Day	5% 8% 31% 33% 18% 5%	630
July	1st to 10th	Day	11% 4 17% 28% 28% 12%	621
	11th to 20th	Day	5% 4 20% 39% 25% 6%	618
	21st to end	Day	8% 4 20% 35% 27% 6%	684
August	1st to 10th	Day	10% 1 20% 33% 26% 8%	582
	11th to 20th	Day	12% 3 20% 31% 26% 8%	439
	21st to end	Day	10% 4 16% 31% 27% 12%	495
September	1st to 10th	Day	13% 4 18% 33% 25% 7%	450
	11th to 20th	Day	7% 4 19% 33% 28% 9%	450
	21st to end	Day	11% 10% 23% 29% 19% 8%	450
October	1st to 10th	Day	10% 11% 31% 34% 12% 2	288
	11th to 20th	Day	21% 19% 34% 20% 5%	270
	21st to end	Day	29% 21% 32% 16% 2	297
November	1st to 10th	Day	12% 17% 43% 19% 6% 3	270
	11th to 20th	Day	21% 23% 30% 18% 8% 1	270
	21st to end	Day	24% 20% 36% 16% 3 1	270
December	1st to 10th	Day	19% 22% 39% 11% 7% 3	270
	11th to 20th	Day	28% 21% 34% 15% 2	270
	21st to end	Day	28% 26% 33% 11% 2	297
January	1st to 10th	Night	20% 25% 35% 17% 3	950
	11th to 20th	Night	24% 27% 31% 15% 3	950
	21st to end	Night	21% 23% 37% 18% 1	1043
February	1st to 10th	Night	23% 24% 35% 17% 2	881
	11th to 20th	Night	22% 24% 36% 16% 2	703
	21st to end	Night	25% 23% 32% 19% 1	592
March	1st to 10th	Night	24% 20% 36% 17% 3	720
	11th to 20th	Night	21% 19% 33% 23% 3	540
	21st to end	Night	24% 15% 33% 24% 5%	594
April	1st to 10th	Night	12% 21% 36% 27% 4	540
	11th to 20th	Night	19% 16% 31% 24% 9%	533
	21st to end	Night	22% 13% 36% 22% 7%	540
May	1st to 10th	Night	16% 11% 33% 31% 8% 1	540
	11th to 20th	Night	19% 6% 31% 28% 14% 2	531
	21st to end	Night	9% 5% 29% 35% 18% 3	584
June	1st to 10th	Night	11% 4 22% 36% 26% 1	540
	11th to 20th	Night	6% 3 24% 43% 21% 1	540
	21st to end	Night	5% 2 27% 40% 24% 2	540
July	1st to 10th	Night	8% 2 13% 35% 34% 8%	525
	11th to 20th	Night	6% 2 16% 39% 32% 4	522
	21st to end	Night	8% 1 16% 39% 31% 4	591
August	1st to 10th	Night	8% 2 15% 36% 34% 5%	537
	11th to 20th	Night	7% 2 15% 38% 34% 4	534
	21st to end	Night	7% 3 15% 36% 33% 7%	594
September	1st to 10th	Night	13% 3 15% 34% 29% 6%	540
	11th to 20th	Night	10% 3 14% 36% 31% 6%	556
	21st to end	Night	11% 7% 24% 28% 24% 6%	720
October	1st to 10th	Night	7% 5% 31% 31% 20% 5%	720
	11th to 20th	Night	18% 14% 30% 26% 12% 1	720
	21st to end	Night	24% 15% 33% 21% 6%	792
November	1st to 10th	Night	13% 11% 41% 25% 9% 1	740
	11th to 20th	Night	17% 19% 33% 24% 7% 1	760
	21st to end	Night	23% 18% 34% 19% 6%	769
December	1st to 10th	Night	22% 18% 34% 20% 5% 1	950
	11th to 20th	Night	22% 15% 38% 21% 4	950
	21st to end	Night	24% 22% 35% 16% 3	1045

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