Weiser State Forest
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Weiser State Forest clear sky chart from 2005-11-06 to 2026-05-02.

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% 8% 3 7% 5% 4 5% 4 6% 7% 36%	131959
	Night	15% 8% 3 8% 5% 4 4 3 5% 7% 38%	130530
Transparency	Day	45% 5% 12% 22% 14% 2	135551
	Night	44% 5% 12% 22% 15% 2	135025
Seeing	Day	25% 15% 27% 20% 10% 3	16706
	Night	21% 14% 26% 27% 10% 1	26204

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	13% 10% 3 12% 6% 4 5% 3 4 5% 35%	4661
	11th to 20th	Day	12% 13% 5% 13% 6% 5% 4 3 5% 6% 29%	5044
	21st to end	Day	15% 8% 4 9% 7% 5% 4 4 5% 5% 35%	5780
February	1st to 10th	Day	15% 11% 4 8% 5% 6% 5% 4 5% 6% 33%	1890
	11th to 20th	Day	15% 10% 5% 9% 5% 4 4 4 6% 7% 32%	1895
	21st to end	Day	17% 11% 5% 8% 5% 4 4 3 4 6% 33%	1730
March	1st to 10th	Day	20% 7% 3 6% 4 4 4 3 4 5% 39%	4846
	11th to 20th	Day	11% 8% 2 8% 5% 4 4 3 5% 7% 41%	5090
	21st to end	Day	16% 8% 3 6% 4 4 4 4 5% 5% 40%	5758
April	1st to 10th	Day	16% 9% 4 8% 5% 5% 4 4 5% 6% 35%	2520
	11th to 20th	Day	15% 8% 2 7% 4 5% 4 4 5% 7% 39%	2494
	21st to end	Day	17% 6% 3 7% 4 4 4 4 6% 7% 38%	2520
May	1st to 10th	Day	26% 8% 2 6% 4 4 4 3 5% 7% 30%	5936
	11th to 20th	Day	23% 8% 3 7% 5% 5% 5% 4 5% 8% 28%	6318
	21st to end	Day	18% 7% 3 6% 4 4 5% 4 6% 8% 34%	6949
June	1st to 10th	Day	13% 7% 2 6% 6% 5% 4 4 7% 8% 38%	2800
	11th to 20th	Day	14% 7% 2 6% 6% 4 5% 5% 7% 8% 36%	2800
	21st to end	Day	11% 5% 2 6% 4 5% 5% 5% 7% 10% 41%	2800
July	1st to 10th	Day	7% 5% 3 8% 6% 6% 6% 5% 7% 10% 39%	6360
	11th to 20th	Day	9% 7% 3 8% 6% 5% 7% 5% 8% 11% 32%	6360
	21st to end	Day	11% 6% 3 7% 5% 4 5% 4 6% 9% 39%	6561
August	1st to 10th	Day	17% 8% 2 6% 5% 5% 5% 5% 6% 9% 32%	4234
	11th to 20th	Day	14% 7% 2 6% 4 4 5% 4 7% 8% 38%	4017
	21st to end	Day	12% 6% 2 5% 3 3 3 3 5% 8% 48%	4312
September	1st to 10th	Day	16% 5% 2 6% 4 3 4 3 5% 7% 47%	2400
	11th to 20th	Day	13% 5% 2 5% 4 3 4 3 6% 7% 50%	2400
	21st to end	Day	22% 9% 2 6% 3 4 3 4 4 6% 37%	2116
October	1st to 10th	Day	18% 5% 1 6% 3 4 4 3 5% 8% 43%	2000
	11th to 20th	Day	18% 6% 2 5% 4 4 3 3 6% 7% 41%	2000
	21st to end	Day	17% 7% 3 7% 4 3 4 4 5% 7% 39%	2200
November	1st to 10th	Day	13% 7% 2 5% 3 3 3 3 6% 7% 48%	1866
	11th to 20th	Day	17% 7% 3 7% 4 4 5% 4 5% 6% 39%	1828
	21st to end	Day	17% 8% 3 6% 5% 4 6% 4 5% 6% 36%	1680
December	1st to 10th	Day	15% 8% 4 8% 4 6% 5% 3 5% 6% 35%	2680
	11th to 20th	Day	21% 9% 3 7% 4 3 4 3 5% 6% 35%	3066
	21st to end	Day	16% 12% 4 11% 5% 5% 5% 3 6% 6% 26%	4048
January	1st to 10th	Night	11% 11% 4 13% 7% 4 4 3 5% 7% 31%	8234
	11th to 20th	Night	12% 9% 4 11% 7% 5% 5% 4 5% 5% 34%	7837
	21st to end	Night	14% 7% 3 7% 5% 5% 5% 3 5% 6% 39%	8401
February	1st to 10th	Night	15% 10% 3 7% 5% 5% 5% 4 5% 6% 35%	2730
	11th to 20th	Night	16% 10% 3 8% 5% 5% 5% 4 5% 7% 33%	2610
	21st to end	Night	16% 9% 4 7% 5% 5% 4 3 5% 6% 35%	2076
March	1st to 10th	Night	18% 11% 3 8% 4 4 4 3 4 4 38%	5212
	11th to 20th	Night	11% 8% 3 7% 4 4 4 3 4 5% 47%	5089
	21st to end	Night	15% 9% 3 7% 4 4 5% 3 4 5% 41%	5414
April	1st to 10th	Night	18% 10% 3 7% 5% 4 4 3 6% 7% 33%	2100
	11th to 20th	Night	15% 7% 3 6% 5% 4 4 4 6% 8% 38%	2075
	21st to end	Night	17% 6% 3 6% 4 4 3 3 5% 8% 42%	2100
May	1st to 10th	Night	27% 8% 3 7% 4 4 4 3 5% 7% 28%	4053
	11th to 20th	Night	21% 9% 3 8% 4 4 4 3 5% 7% 31%	3575
	21st to end	Night	20% 7% 2 7% 4 4 4 3 5% 8% 37%	3926
June	1st to 10th	Night	14% 6% 2 6% 4 4 5% 4 5% 7% 44%	1600
	11th to 20th	Night	13% 6% 3 6% 5% 5% 4 4 5% 9% 40%	1600
	21st to end	Night	11% 5% 2 5% 5% 5% 6% 4 7% 9% 42%	1600
July	1st to 10th	Night	10% 7% 3 8% 4 5% 5% 4 7% 9% 40%	3600
	11th to 20th	Night	11% 7% 3 9% 6% 6% 6% 5% 7% 9% 32%	3600
	21st to end	Night	12% 6% 2 5% 4 5% 4 4 6% 8% 43%	4286
August	1st to 10th	Night	19% 7% 3 6% 4 4 3 4 6% 8% 35%	2915
	11th to 20th	Night	13% 8% 3 7% 5% 4 4 3 6% 7% 40%	2997
	21st to end	Night	10% 5% 2 6% 4 5% 4 4 6% 8% 46%	3586
September	1st to 10th	Night	14% 6% 2 6% 4 4 3 3 5% 7% 48%	2000
	11th to 20th	Night	11% 5% 3 4 4 3 4 3 5% 7% 53%	2000
	21st to end	Night	18% 8% 2 7% 4 3 5% 3 5% 6% 39%	2278
October	1st to 10th	Night	19% 6% 2 5% 4 3 3 2 5% 6% 45%	2400
	11th to 20th	Night	16% 7% 2 5% 4 3 4 3 5% 6% 46%	2400
	21st to end	Night	17% 7% 2 6% 3 3 4 4 5% 7% 42%	2640
November	1st to 10th	Night	11% 6% 2 5% 4 4 3 3 6% 6% 50%	2650
	11th to 20th	Night	15% 9% 3 7% 4 3 3 3 5% 6% 41%	2788
	21st to end	Night	16% 8% 3 7% 5% 4 5% 3 5% 8% 37%	2940
December	1st to 10th	Night	13% 10% 4 8% 5% 4 5% 4 5% 7% 38%	4720
	11th to 20th	Night	21% 9% 3 7% 4 4 4 3 5% 5% 35%	5348
	21st to end	Night	18% 11% 3 9% 6% 5% 4 3 5% 6% 29%	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	49% 3 11% 23% 12% 2	4662
	11th to 20th	Day	56% 3 9% 14% 13% 5%	5078
	21st to end	Day	51% 4 12% 20% 13%	5780
February	1st to 10th	Day	50% 6% 11% 21% 11% 1	1890
	11th to 20th	Day	50% 5% 11% 22% 10% 2	1904
	21st to end	Day	52% 4 12% 20% 9% 3	1730
March	1st to 10th	Day	46% 5% 9% 23% 12% 6%	4849
	11th to 20th	Day	41% 4 14% 25% 10% 5%	5090
	21st to end	Day	45% 4 10% 18% 19% 4	5758
April	1st to 10th	Day	48% 5% 10% 18% 14% 4	2520
	11th to 20th	Day	44% 5% 12% 20% 15% 4	2494
	21st to end	Day	44% 5% 10% 22% 15% 4	2520
May	1st to 10th	Day	54% 5% 11% 18% 10% 2	5945
	11th to 20th	Day	53% 6% 9% 20% 10% 1	6322
	21st to end	Day	45% 6% 11% 23% 14% 2	6949
June	1st to 10th	Day	41% 8% 12% 22% 16% 2	2800
	11th to 20th	Day	43% 8% 13% 21% 12% 2	2800
	21st to end	Day	36% 9% 14% 26% 15% 1	2800
July	1st to 10th	Day	41% 7% 12% 24% 15% 1	6290
	11th to 20th	Day	46% 5% 16% 22% 10% 1	6285
	21st to end	Day	43% 4 10% 21% 21% 1	6374
August	1st to 10th	Day	48% 7% 14% 22% 9%	4221
	11th to 20th	Day	42% 5% 10% 29% 13% 1	4056
	21st to end	Day	35% 4 10% 31% 17% 2	4312
September	1st to 10th	Day	39% 5% 11% 22% 20% 3	2400
	11th to 20th	Day	34% 5% 11% 25% 22% 3	2400
	21st to end	Day	49% 5% 9% 16% 19% 2	2116
October	1st to 10th	Day	37% 4 8% 24% 21% 5%	3260
	11th to 20th	Day	33% 3 11% 27% 20% 5%	3240
	21st to end	Day	29% 4 13% 29% 24% 2	3538
November	1st to 10th	Day	35% 5% 15% 23% 19% 3	1866
	11th to 20th	Day	44% 5% 12% 22% 15% 3	1828
	21st to end	Day	45% 6% 12% 26% 9% 1	1680
December	1st to 10th	Day	49% 4 15% 23% 9% 2	2680
	11th to 20th	Day	50% 4 14% 25% 7% 1	3066
	21st to end	Day	54% 6% 15% 15% 9% 1	4048
January	1st to 10th	Night	48% 5% 14% 20% 12% 2	8234
	11th to 20th	Night	49% 3 11% 17% 16% 4	7878
	21st to end	Night	45% 4 10% 24% 16% 1	8401
February	1st to 10th	Night	47% 7% 12% 24% 10% 1	2730
	11th to 20th	Night	49% 5% 12% 19% 14% 1	2612
	21st to end	Night	48% 4 11% 20% 14% 3	2076
March	1st to 10th	Night	47% 4 10% 21% 12% 6%	5222
	11th to 20th	Night	38% 5% 16% 26% 10% 5%	5090
	21st to end	Night	45% 4 8% 18% 23% 3	5414
April	1st to 10th	Night	49% 5% 11% 19% 14% 3	2100
	11th to 20th	Night	41% 7% 12% 20% 18% 2	2075
	21st to end	Night	41% 5% 11% 22% 17% 4	2100
May	1st to 10th	Night	56% 5% 9% 16% 10% 3	4060
	11th to 20th	Night	51% 8% 12% 18% 11% 1	3576
	21st to end	Night	47% 6% 10% 21% 13% 3	3927
June	1st to 10th	Night	38% 8% 11% 22% 20% 2	1600
	11th to 20th	Night	40% 7% 13% 22% 16% 2	1600
	21st to end	Night	36% 7% 15% 25% 16% 1	1600
July	1st to 10th	Night	41% 7% 14% 19% 15% 3	3560
	11th to 20th	Night	49% 5% 14% 21% 11% 1	3552
	21st to end	Night	38% 4 12% 22% 22% 1	4159
August	1st to 10th	Night	47% 5% 15% 21% 10% 1	2904
	11th to 20th	Night	43% 6% 10% 25% 16% 1	3024
	21st to end	Night	35% 5% 11% 31% 16% 1	3586
September	1st to 10th	Night	37% 6% 10% 23% 21% 3	2000
	11th to 20th	Night	33% 5% 9% 27% 23% 3	2000
	21st to end	Night	46% 4 9% 18% 20% 2	2278
October	1st to 10th	Night	41% 3 9% 23% 22% 1	3920
	11th to 20th	Night	31% 4 9% 29% 21% 6%	3899
	21st to end	Night	29% 4 13% 31% 22% 2	4252
November	1st to 10th	Night	34% 5% 12% 26% 20% 4	2650
	11th to 20th	Night	43% 4 10% 24% 16% 4	2788
	21st to end	Night	44% 6% 13% 25% 11% 1	2940
December	1st to 10th	Night	46% 4 14% 27% 9%	4720
	11th to 20th	Night	49% 3 14% 22% 10% 1	5348
	21st to end	Night	53% 5% 12% 17% 12% 1	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	36% 26% 26% 9% 4	220
	11th to 20th	Day	47% 19% 26% 7% 1	293
	21st to end	Day	33% 30% 26% 8% 3	363
February	1st to 10th	Day	32% 28% 31% 8% 2	330
	11th to 20th	Day	39% 24% 30% 6% 1	382
	21st to end	Day	36% 21% 28% 12% 2	446
March	1st to 10th	Day	36% 18% 29% 14% 4	540
	11th to 20th	Day	33% 23% 27% 13% 3 1	540
	21st to end	Day	33% 23% 27% 11% 4 1	594
April	1st to 10th	Day	34% 20% 26% 14% 5% 1	540
	11th to 20th	Day	26% 24% 26% 15% 7% 3	532
	21st to end	Day	28% 17% 35% 11% 6% 3	540
May	1st to 10th	Day	33% 16% 29% 14% 6% 2	507
	11th to 20th	Day	27% 15% 28% 20% 8% 2	527
	21st to end	Day	21% 10% 28% 23% 14% 4	573
June	1st to 10th	Day	20% 14% 26% 24% 13% 3	530
	11th to 20th	Day	20% 11% 28% 26% 13% 2	530
	21st to end	Day	14% 11% 32% 28% 13% 3	530
July	1st to 10th	Day	13% 6% 25% 29% 21% 6%	525
	11th to 20th	Day	9% 5% 27% 32% 21% 5%	524
	21st to end	Day	14% 5% 28% 34% 16% 5%	576
August	1st to 10th	Day	13% 7% 24% 28% 20% 8%	526
	11th to 20th	Day	11% 5% 24% 34% 19% 7%	519
	21st to end	Day	13% 6% 28% 29% 13% 11%	583
September	1st to 10th	Day	18% 9% 22% 24% 17% 11%	530
	11th to 20th	Day	12% 7% 24% 29% 19% 9%	530
	21st to end	Day	29% 12% 23% 19% 13% 4	530
October	1st to 10th	Day	23% 7% 24% 22% 17% 7%	530
	11th to 20th	Day	23% 15% 28% 22% 10% 2	530
	21st to end	Day	22% 17% 32% 20% 9% 1	583
November	1st to 10th	Day	22% 17% 27% 23% 10% 2	433
	11th to 20th	Day	30% 17% 29% 17% 7% 1	368
	21st to end	Day	33% 20% 33% 10% 3	220
December	1st to 10th	Day	35% 22% 31% 8% 4	220
	11th to 20th	Day	36% 23% 31% 7% 3	220
	21st to end	Day	32% 22% 31% 12% 3	242
January	1st to 10th	Night	25% 23% 32% 18% 3	840
	11th to 20th	Night	28% 19% 29% 21% 3	840
	21st to end	Night	23% 22% 32% 21% 2	924
February	1st to 10th	Night	26% 19% 30% 23% 2	840
	11th to 20th	Night	28% 24% 33% 15% 1	823
	21st to end	Night	28% 22% 31% 17% 3	692
March	1st to 10th	Night	27% 20% 31% 19% 4	840
	11th to 20th	Night	28% 18% 30% 19% 4	840
	21st to end	Night	24% 20% 32% 17% 6%	924
April	1st to 10th	Night	26% 20% 30% 19% 4	840
	11th to 20th	Night	21% 16% 34% 23% 6% 1	831
	21st to end	Night	22% 15% 28% 29% 6%	840
May	1st to 10th	Night	26% 9% 28% 26% 11%	607
	11th to 20th	Night	21% 7% 30% 32% 11%	394
	21st to end	Night	15% 9% 21% 38% 16% 1	433
June	1st to 10th	Night	16% 7% 23% 36% 20%	400
	11th to 20th	Night	17% 4 24% 41% 14% 1	400
	21st to end	Night	12% 5% 24% 45% 15% 1	400
July	1st to 10th	Night	14% 3 18% 42% 20% 3	390
	11th to 20th	Night	11% 2 14% 44% 27% 2	388
	21st to end	Night	12% 3 18% 39% 26% 2	593
August	1st to 10th	Night	15% 3 11% 43% 28% 2	597
	11th to 20th	Night	14% 4 12% 38% 28% 4	664
	21st to end	Night	12% 4 18% 35% 27% 3	880
September	1st to 10th	Night	16% 4 21% 36% 21% 3	800
	11th to 20th	Night	13% 4 18% 37% 24% 5%	800
	21st to end	Night	21% 8% 20% 31% 18% 2	800
October	1st to 10th	Night	22% 8% 19% 29% 19% 3	800
	11th to 20th	Night	19% 12% 26% 31% 11% 1	800
	21st to end	Night	23% 13% 28% 28% 8%	880
November	1st to 10th	Night	17% 13% 30% 30% 10% 1	820
	11th to 20th	Night	23% 19% 27% 23% 7% 1	840
	21st to end	Night	24% 18% 29% 23% 6%	840
December	1st to 10th	Night	26% 19% 30% 20% 4	840
	11th to 20th	Night	24% 18% 30% 25% 3	840
	21st to end	Night	25% 21% 27% 26% 2	924

Page generated at 2026-04-29 02:21:44. Version ac07

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