James Baird State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the James Baird State Park clear sky chart from 2005-11-06 to 2026-08-15.

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	16% 7% 3 7% 4 4 4 4 5% 7% 38%	143884
	Night	17% 8% 3 7% 4 4 4 3 5% 7% 38%	137995
Transparency	Day	44% 6% 12% 22% 15% 2	147400
	Night	44% 6% 11% 21% 15% 2	142568
Seeing	Day	23% 17% 28% 20% 9% 3	17191
	Night	22% 14% 30% 26% 8% 1	26212

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	12% 9% 3 9% 6% 5% 5% 4 5% 6% 38%	4661
	11th to 20th	Day	14% 9% 3 8% 5% 4 4 3 5% 5% 39%	4650
	21st to end	Day	15% 7% 3 7% 4 3 4 4 5% 7% 40%	5423
February	1st to 10th	Day	16% 8% 3 8% 5% 5% 4 4 5% 7% 34%	1892
	11th to 20th	Day	14% 9% 3 9% 5% 4 4 4 5% 6% 36%	2048
	21st to end	Day	18% 9% 3 6% 5% 4 4 3 5% 5% 37%	1730
March	1st to 10th	Day	22% 9% 3 7% 4 4 3 3 4 4 37%	4576
	11th to 20th	Day	12% 8% 3 7% 4 4 4 3 5% 6% 42%	4826
	21st to end	Day	19% 8% 2 7% 4 4 4 4 4 6% 36%	6093
April	1st to 10th	Day	19% 10% 4 6% 5% 3 4 3 5% 6% 36%	2520
	11th to 20th	Day	16% 8% 3 6% 5% 5% 4 3 4 7% 39%	2494
	21st to end	Day	20% 6% 2 6% 5% 4 5% 3 4 6% 39%	2587
May	1st to 10th	Day	24% 8% 2 6% 4 4 4 3 5% 8% 31%	7639
	11th to 20th	Day	18% 8% 3 7% 4 4 4 3 5% 7% 38%	8220
	21st to end	Day	21% 7% 3 6% 4 5% 5% 4 6% 8% 31%	9060
June	1st to 10th	Day	16% 5% 2 6% 4 5% 6% 4 7% 9% 37%	2940
	11th to 20th	Day	15% 6% 3 6% 4 5% 5% 5% 7% 9% 36%	2940
	21st to end	Day	12% 6% 2 7% 5% 5% 5% 4 6% 9% 38%	2940
July	1st to 10th	Day	13% 7% 3 7% 5% 5% 5% 4 7% 9% 35%	8280
	11th to 20th	Day	9% 5% 2 6% 5% 5% 6% 5% 7% 11% 40%	8280
	21st to end	Day	14% 6% 3 6% 4 4 4 4 5% 8% 41%	8993
August	1st to 10th	Day	18% 7% 3 7% 5% 6% 5% 5% 6% 7% 31%	4553
	11th to 20th	Day	12% 6% 2 6% 4 4 5% 5% 7% 8% 41%	3898
	21st to end	Day	10% 6% 2 6% 4 5% 4 4 6% 10% 44%	4312
September	1st to 10th	Day	13% 8% 2 5% 4 4 5% 4 6% 7% 43%	2400
	11th to 20th	Day	12% 5% 1 5% 4 4 5% 3 6% 7% 50%	2305
	21st to end	Day	17% 6% 3 6% 4 3 5% 4 6% 7% 40%	2200
October	1st to 10th	Day	20% 6% 2 5% 4 3 4 3 4 6% 43%	2100
	11th to 20th	Day	14% 7% 2 6% 4 4 4 4 4 7% 43%	2000
	21st to end	Day	21% 6% 2 6% 5% 4 5% 4 5% 6% 37%	2009
November	1st to 10th	Day	13% 6% 2 5% 4 4 4 3 4 7% 48%	1851
	11th to 20th	Day	16% 7% 2 6% 3 4 4 3 6% 6% 42%	1890
	21st to end	Day	18% 8% 3 6% 5% 4 3 3 5% 6% 40%	1780
December	1st to 10th	Day	17% 8% 3 5% 4 4 4 3 5% 7% 39%	2680
	11th to 20th	Day	21% 8% 2 6% 3 3 4 3 5% 7% 39%	3066
	21st to end	Day	18% 10% 4 9% 5% 4 3 3 4 7% 33%	4048
January	1st to 10th	Night	15% 9% 3 9% 5% 5% 5% 3 5% 6% 36%	8234
	11th to 20th	Night	14% 9% 4 10% 6% 5% 5% 4 5% 7% 33%	8235
	21st to end	Night	15% 9% 3 7% 5% 5% 4 4 5% 6% 38%	8741
February	1st to 10th	Night	14% 11% 3 7% 5% 4 4 4 4 6% 38%	2726
	11th to 20th	Night	15% 9% 3 8% 5% 4 4 4 6% 7% 35%	2458
	21st to end	Night	17% 9% 3 7% 5% 4 4 4 4 6% 37%	2076
March	1st to 10th	Night	21% 8% 2 5% 4 4 4 3 4 6% 39%	5484
	11th to 20th	Night	15% 9% 3 7% 4 4 4 3 5% 6% 40%	5337
	21st to end	Night	20% 10% 3 7% 4 4 4 3 5% 5% 36%	5079
April	1st to 10th	Night	19% 8% 3 8% 5% 4 4 5% 5% 7% 32%	2100
	11th to 20th	Night	20% 8% 2 6% 4 4 4 3 5% 6% 37%	2075
	21st to end	Night	20% 9% 3 6% 3 3 3 3 4 6% 40%	2032
May	1st to 10th	Night	28% 8% 2 6% 3 4 4 3 5% 7% 31%	5259
	11th to 20th	Night	18% 8% 3 8% 5% 4 3 4 5% 7% 35%	4682
	21st to end	Night	21% 8% 3 7% 4 4 4 3 5% 7% 33%	5114
June	1st to 10th	Night	15% 6% 3 6% 4 5% 5% 3 6% 7% 41%	1680
	11th to 20th	Night	14% 8% 2 6% 4 4 5% 4 6% 9% 39%	1680
	21st to end	Night	12% 5% 2 6% 4 3 5% 4 7% 11% 41%	1680
July	1st to 10th	Night	14% 6% 3 6% 4 4 5% 4 7% 9% 36%	4680
	11th to 20th	Night	12% 6% 2 7% 5% 5% 5% 5% 7% 9% 38%	4680
	21st to end	Night	13% 7% 2 6% 4 4 4 4 5% 7% 44%	5084
August	1st to 10th	Night	20% 7% 3 7% 4 5% 5% 5% 5% 7% 31%	2780
	11th to 20th	Night	13% 7% 3 7% 5% 4 5% 4 6% 7% 39%	3238
	21st to end	Night	12% 4 2 5% 3 3 5% 3 5% 7% 51%	3586
September	1st to 10th	Night	15% 7% 2 6% 4 3 3 3 4 7% 46%	2000
	11th to 20th	Night	11% 5% 2 4 3 4 3 2 5% 7% 53%	2095
	21st to end	Night	17% 6% 3 5% 3 3 3 4 6% 6% 44%	2200
October	1st to 10th	Night	19% 6% 3 6% 4 3 3 3 4 6% 42%	2297
	11th to 20th	Night	15% 6% 2 6% 3 4 4 3 5% 7% 44%	2400
	21st to end	Night	20% 7% 2 7% 4 4 3 3 5% 6% 38%	2830
November	1st to 10th	Night	13% 8% 2 6% 3 3 4 3 5% 8% 45%	2667
	11th to 20th	Night	18% 8% 2 5% 4 4 4 3 5% 5% 42%	2730
	21st to end	Night	15% 8% 3 6% 5% 4 4 3 5% 7% 40%	2838
December	1st to 10th	Night	17% 9% 3 6% 4 4 4 3 5% 6% 39%	4720
	11th to 20th	Night	24% 9% 3 6% 3 3 3 3 5% 5% 35%	5348
	21st to end	Night	19% 12% 4 7% 5% 3 4 3 5% 5% 33%	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	46% 4 10% 25% 13% 2	4662
	11th to 20th	Day	46% 4 9% 21% 14% 6%	4680
	21st to end	Day	43% 6% 10% 25% 16% 1	5423
February	1st to 10th	Day	48% 6% 12% 19% 14% 1	1892
	11th to 20th	Day	47% 5% 10% 21% 15% 2	2057
	21st to end	Day	49% 5% 11% 22% 12% 2	1730
March	1st to 10th	Day	50% 4 10% 17% 11% 8%	4579
	11th to 20th	Day	40% 5% 14% 29% 9% 4	4826
	21st to end	Day	49% 5% 8% 13% 21% 5%	6093
April	1st to 10th	Day	49% 4 10% 20% 13% 3	2520
	11th to 20th	Day	44% 5% 12% 21% 16% 2	2494
	21st to end	Day	45% 5% 11% 20% 16% 3	2587
May	1st to 10th	Day	52% 6% 12% 17% 12% 1	7651
	11th to 20th	Day	46% 6% 12% 23% 14% 1	8224
	21st to end	Day	49% 6% 11% 21% 12% 1	9061
June	1st to 10th	Day	42% 8% 13% 22% 14% 1	2940
	11th to 20th	Day	44% 7% 13% 23% 11% 2	2940
	21st to end	Day	43% 8% 12% 23% 13% 1	2940
July	1st to 10th	Day	45% 8% 12% 20% 14% 1	8210
	11th to 20th	Day	37% 7% 15% 29% 12% 1	8205
	21st to end	Day	41% 5% 11% 24% 18% 1	8795
August	1st to 10th	Day	49% 8% 13% 20% 9% 1	4539
	11th to 20th	Day	37% 8% 16% 29% 10%	3934
	21st to end	Day	34% 6% 12% 31% 15% 1	4312
September	1st to 10th	Day	39% 8% 10% 24% 18% 2	2400
	11th to 20th	Day	34% 6% 9% 26% 24% 2	2305
	21st to end	Day	43% 7% 11% 21% 17% 3	2200
October	1st to 10th	Day	39% 6% 8% 19% 25% 3	3425
	11th to 20th	Day	31% 5% 10% 25% 25% 4	3240
	21st to end	Day	32% 5% 15% 25% 20% 3	3221
November	1st to 10th	Day	36% 6% 13% 26% 18% 2	1851
	11th to 20th	Day	40% 5% 12% 23% 18% 3	1890
	21st to end	Day	45% 4 13% 27% 9% 2	1780
December	1st to 10th	Day	44% 4 16% 27% 9% 1	2680
	11th to 20th	Day	45% 4 15% 21% 14% 2	3066
	21st to end	Day	51% 4 8% 20% 14% 2	4048
January	1st to 10th	Night	47% 5% 11% 21% 15% 2	8234
	11th to 20th	Night	49% 5% 11% 18% 12% 5%	8280
	21st to end	Night	46% 4 9% 20% 18% 3	8741
February	1st to 10th	Night	47% 6% 12% 22% 12% 2	2726
	11th to 20th	Night	47% 6% 10% 17% 16% 3	2460
	21st to end	Night	46% 5% 10% 22% 13% 4	2076
March	1st to 10th	Night	45% 6% 12% 17% 15% 6%	5494
	11th to 20th	Night	43% 5% 16% 23% 10% 4	5338
	21st to end	Night	49% 5% 6% 13% 23% 4	5079
April	1st to 10th	Night	51% 6% 10% 17% 14% 2	2100
	11th to 20th	Night	48% 5% 9% 19% 17% 1	2075
	21st to end	Night	46% 5% 9% 21% 17% 3	2032
May	1st to 10th	Night	54% 6% 12% 16% 12% 1	5265
	11th to 20th	Night	48% 7% 12% 21% 11% 2	4683
	21st to end	Night	50% 6% 11% 21% 9% 1	5115
June	1st to 10th	Night	42% 7% 10% 23% 16% 2	1680
	11th to 20th	Night	41% 8% 16% 24% 10% 1	1680
	21st to end	Night	36% 9% 15% 25% 14% 1	1680
July	1st to 10th	Night	43% 8% 14% 20% 13% 1	4640
	11th to 20th	Night	42% 8% 13% 24% 13% 1	4632
	21st to end	Night	38% 7% 11% 26% 18% 1	4967
August	1st to 10th	Night	51% 9% 12% 18% 9% 1	2770
	11th to 20th	Night	42% 7% 14% 28% 9%	3268
	21st to end	Night	32% 6% 12% 35% 15% 1	3586
September	1st to 10th	Night	39% 6% 9% 27% 18% 1	2000
	11th to 20th	Night	31% 5% 10% 25% 26% 1	2095
	21st to end	Night	41% 6% 10% 21% 22% 1	2200
October	1st to 10th	Night	41% 7% 9% 22% 19% 2	3752
	11th to 20th	Night	29% 5% 10% 28% 26% 2	3899
	21st to end	Night	34% 5% 13% 29% 18% 1	4568
November	1st to 10th	Night	37% 6% 11% 23% 20% 3	2667
	11th to 20th	Night	43% 5% 9% 21% 19% 3	2730
	21st to end	Night	41% 6% 14% 28% 10% 1	2838
December	1st to 10th	Night	44% 5% 13% 29% 8% 1	4720
	11th to 20th	Night	50% 4 13% 16% 15% 2	5348
	21st to end	Night	51% 4 10% 16% 15% 4	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	29% 28% 25% 14% 5%	220
	11th to 20th	Day	37% 25% 24% 11% 3	220
	21st to end	Day	25% 29% 32% 10% 2 2	297
February	1st to 10th	Day	34% 25% 30% 8% 3	332
	11th to 20th	Day	29% 25% 33% 13%	536
	21st to end	Day	32% 22% 31% 12% 2	446
March	1st to 10th	Day	31% 21% 32% 14% 3	540
	11th to 20th	Day	31% 23% 29% 14% 3 1	540
	21st to end	Day	34% 22% 29% 10% 4 2	594
April	1st to 10th	Day	36% 22% 25% 11% 5% 1	540
	11th to 20th	Day	28% 25% 27% 13% 6% 1	532
	21st to end	Day	29% 18% 31% 15% 5% 1	540
May	1st to 10th	Day	34% 19% 29% 11% 6% 1	543
	11th to 20th	Day	22% 20% 32% 19% 7% 1	567
	21st to end	Day	22% 14% 28% 24% 9% 3	617
June	1st to 10th	Day	20% 12% 30% 24% 12% 2	570
	11th to 20th	Day	18% 15% 30% 24% 12% 2	570
	21st to end	Day	16% 14% 28% 26% 13% 2	570
July	1st to 10th	Day	15% 7% 30% 30% 14% 4	565
	11th to 20th	Day	12% 8% 28% 32% 17% 2	564
	21st to end	Day	14% 9% 30% 30% 13% 3	620
August	1st to 10th	Day	13% 8% 26% 31% 16% 6%	566
	11th to 20th	Day	14% 8% 28% 28% 16% 6%	535
	21st to end	Day	11% 10% 29% 28% 15% 7%	583
September	1st to 10th	Day	19% 11% 24% 22% 16% 7%	530
	11th to 20th	Day	12% 10% 28% 22% 17% 11%	530
	21st to end	Day	22% 11% 26% 25% 11% 5%	530
October	1st to 10th	Day	28% 9% 24% 18% 16% 5%	530
	11th to 20th	Day	21% 18% 28% 22% 10% 2	530
	21st to end	Day	27% 14% 29% 20% 9% 1	477
November	1st to 10th	Day	21% 19% 24% 24% 9% 2	425
	11th to 20th	Day	26% 20% 29% 18% 6% 1	430
	21st to end	Day	27% 21% 29% 19% 4 1	320
December	1st to 10th	Day	24% 27% 30% 14% 5%	220
	11th to 20th	Day	34% 25% 26% 13% 1	220
	21st to end	Day	26% 23% 29% 17% 5%	242
January	1st to 10th	Night	22% 18% 38% 19% 3	840
	11th to 20th	Night	26% 20% 30% 21% 3	840
	21st to end	Night	19% 22% 37% 20% 3	924
February	1st to 10th	Night	24% 18% 33% 23% 1	840
	11th to 20th	Night	25% 20% 37% 17% 1	823
	21st to end	Night	25% 18% 36% 18% 2	692
March	1st to 10th	Night	24% 22% 32% 20% 3	840
	11th to 20th	Night	24% 22% 32% 19% 4	840
	21st to end	Night	24% 21% 34% 17% 4	924
April	1st to 10th	Night	27% 21% 30% 18% 3	840
	11th to 20th	Night	25% 17% 31% 22% 5%	831
	21st to end	Night	25% 17% 33% 20% 5%	772
May	1st to 10th	Night	26% 17% 30% 22% 5%	630
	11th to 20th	Night	20% 13% 35% 28% 4	432
	21st to end	Night	20% 8% 28% 35% 9% 1	455
June	1st to 10th	Night	17% 7% 29% 34% 13%	420
	11th to 20th	Night	17% 7% 30% 31% 15%	420
	21st to end	Night	15% 4 24% 45% 12%	420
July	1st to 10th	Night	16% 3 21% 41% 18% 1	410
	11th to 20th	Night	14% 4 23% 43% 14% 1	408
	21st to end	Night	13% 5% 23% 41% 17% 1	460
August	1st to 10th	Night	14% 2 21% 44% 17% 2	480
	11th to 20th	Night	14% 4 19% 40% 20% 2	807
	21st to end	Night	16% 4 21% 36% 20% 2	880
September	1st to 10th	Night	17% 5% 27% 34% 14% 3	800
	11th to 20th	Night	15% 5% 23% 32% 20% 4	800
	21st to end	Night	21% 6% 25% 31% 15% 2	800
October	1st to 10th	Night	23% 9% 26% 26% 15% 2	800
	11th to 20th	Night	21% 12% 28% 30% 9% 1	800
	21st to end	Night	26% 13% 28% 26% 7%	880
November	1st to 10th	Night	20% 11% 30% 29% 9%	820
	11th to 20th	Night	23% 16% 32% 22% 6% 1	840
	21st to end	Night	20% 18% 31% 25% 6%	840
December	1st to 10th	Night	27% 16% 30% 21% 5%	840
	11th to 20th	Night	25% 16% 32% 23% 4	840
	21st to end	Night	28% 16% 34% 20% 2	924

Page generated at 2026-08-12 03:37:19. Version ac07

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