Elk River WMA
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Elk River WMA clear sky chart from 2005-11-06 to 2026-07-16.

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	17% 10% 3 8% 5% 4 4 4 5% 7% 32%	137299
	Night	18% 11% 4 8% 5% 4 4 3 5% 6% 31%	135387
Transparency	Day	51% 5% 10% 20% 12% 2	140917
	Night	53% 5% 9% 19% 12% 2	139841
Seeing	Day	27% 13% 24% 20% 11% 4	17136
	Night	26% 11% 23% 27% 12% 2	27497

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	18% 21% 8% 14% 7% 3 3 2 3 5% 16%	5258
	11th to 20th	Day	17% 21% 8% 15% 6% 4 3 1 3 3 21%	5280
	21st to end	Day	16% 16% 5% 12% 8% 5% 3 3 4 5% 23%	5780
February	1st to 10th	Day	20% 15% 4 10% 6% 4 4 3 4 5% 25%	1890
	11th to 20th	Day	22% 17% 4 10% 4 4 4 2 4 5% 25%	1897
	21st to end	Day	23% 16% 4 9% 4 3 3 3 4 4 28%	1756
March	1st to 10th	Day	18% 16% 3 6% 4 4 3 3 5% 6% 32%	5045
	11th to 20th	Day	15% 8% 3 6% 4 4 4 3 5% 7% 39%	5090
	21st to end	Day	20% 10% 3 8% 5% 4 4 3 5% 6% 29%	5586
April	1st to 10th	Day	18% 13% 3 6% 4 4 4 3 5% 7% 33%	2372
	11th to 20th	Day	16% 9% 3 6% 4 4 4 3 5% 7% 39%	2522
	21st to end	Day	21% 9% 2 6% 4 4 5% 4 5% 6% 33%	2730
May	1st to 10th	Day	19% 8% 2 8% 6% 5% 6% 4 7% 8% 27%	7616
	11th to 20th	Day	18% 8% 3 7% 5% 5% 5% 4 6% 8% 33%	7626
	21st to end	Day	22% 7% 3 7% 5% 5% 5% 4 6% 8% 30%	8391
June	1st to 10th	Day	13% 6% 3 6% 5% 5% 6% 5% 6% 8% 37%	2730
	11th to 20th	Day	12% 6% 3 7% 5% 6% 5% 5% 7% 10% 33%	2730
	21st to end	Day	13% 6% 3 6% 5% 5% 5% 5% 7% 10% 36%	2730
July	1st to 10th	Day	10% 5% 2 7% 4 5% 5% 4 6% 9% 42%	6030
	11th to 20th	Day	15% 6% 2 7% 5% 5% 5% 5% 8% 9% 32%	5965
	21st to end	Day	17% 7% 3 7% 5% 5% 5% 4 6% 8% 31%	6424
August	1st to 10th	Day	13% 7% 3 7% 6% 6% 5% 5% 7% 9% 32%	4234
	11th to 20th	Day	14% 5% 2 7% 5% 5% 6% 5% 7% 8% 35%	4174
	21st to end	Day	8% 4 1 5% 4 4 5% 4 6% 10% 49%	4449
September	1st to 10th	Day	14% 6% 2 5% 4 4 4 4 5% 7% 45%	2332
	11th to 20th	Day	13% 6% 2 6% 4 5% 6% 4 5% 7% 44%	2200
	21st to end	Day	20% 9% 2 7% 4 3 3 4 5% 7% 36%	2200
October	1st to 10th	Day	18% 5% 2 5% 3 3 3 3 5% 8% 46%	2035
	11th to 20th	Day	18% 8% 2 5% 4 4 3 3 5% 5% 42%	2000
	21st to end	Day	22% 9% 3 5% 3 3 4 3 4 6% 38%	2200
November	1st to 10th	Day	14% 9% 3 6% 4 4 3 4 5% 5% 45%	2000
	11th to 20th	Day	17% 13% 3 6% 3 4 4 3 6% 6% 34%	1890
	21st to end	Day	19% 16% 4 6% 3 5% 4 3 4 6% 31%	1758
December	1st to 10th	Day	22% 13% 4 18% 4 3 4 3 3 4 22%	2680
	11th to 20th	Day	24% 16% 4 8% 4 3 3 4 5% 6% 24%	3134
	21st to end	Day	19% 16% 5% 10% 6% 5% 5% 4 5% 7% 19%	4565
January	1st to 10th	Night	20% 20% 6% 15% 4 3 3 3 4 5% 18%	7635
	11th to 20th	Night	19% 17% 7% 18% 6% 3 2 2 3 4 19%	7680
	21st to end	Night	21% 12% 4 10% 8% 5% 3 2 3 4 26%	8401
February	1st to 10th	Night	20% 16% 5% 9% 6% 4 3 3 4 5% 26%	2730
	11th to 20th	Night	22% 17% 4 10% 6% 3 4 3 4 4 24%	2605
	21st to end	Night	23% 14% 6% 8% 4 3 3 3 4 7% 25%	2048
March	1st to 10th	Night	23% 11% 3 6% 4 4 3 3 4 6% 33%	5028
	11th to 20th	Night	16% 12% 4 5% 3 3 3 3 4 7% 41%	5090
	21st to end	Night	18% 12% 3 7% 4 5% 5% 4 5% 6% 32%	5588
April	1st to 10th	Night	19% 13% 3 6% 4 4 3 4 4 6% 34%	2247
	11th to 20th	Night	16% 8% 2 6% 4 4 4 4 7% 8% 37%	2065
	21st to end	Night	17% 8% 2 8% 5% 5% 4 4 5% 7% 36%	1890
May	1st to 10th	Night	23% 10% 3 8% 5% 5% 4 3 5% 7% 27%	5237
	11th to 20th	Night	15% 8% 3 7% 5% 5% 5% 4 7% 9% 32%	5234
	21st to end	Night	27% 9% 4 8% 5% 4 4 3 5% 6% 26%	5761
June	1st to 10th	Night	13% 6% 2 6% 4 5% 5% 5% 6% 8% 40%	1890
	11th to 20th	Night	11% 6% 3 7% 5% 5% 5% 5% 7% 9% 36%	1890
	21st to end	Night	13% 6% 2 5% 4 4 4 4 8% 10% 41%	1890
July	1st to 10th	Night	13% 6% 3 7% 5% 5% 5% 4 6% 10% 36%	4148
	11th to 20th	Night	17% 6% 2 7% 5% 4 5% 4 8% 10% 32%	4102
	21st to end	Night	14% 7% 3 8% 5% 5% 5% 5% 7% 9% 32%	4427
August	1st to 10th	Night	16% 7% 3 8% 5% 5% 5% 5% 7% 9% 31%	2915
	11th to 20th	Night	18% 6% 3 7% 4 5% 4 3 6% 7% 36%	2875
	21st to end	Night	7% 5% 1 6% 4 5% 5% 4 5% 9% 48%	3416
September	1st to 10th	Night	13% 6% 2 5% 4 5% 5% 4 6% 7% 44%	2063
	11th to 20th	Night	13% 5% 2 4 3 4 4 2 5% 6% 51%	2200
	21st to end	Night	17% 7% 2 6% 4 5% 5% 3 5% 6% 40%	2200
October	1st to 10th	Night	15% 4 2 6% 4 3 4 4 5% 7% 47%	2365
	11th to 20th	Night	18% 7% 2 5% 4 4 4 3 5% 7% 42%	2400
	21st to end	Night	23% 8% 2 6% 4 3 4 3 4 5% 40%	2640
November	1st to 10th	Night	14% 9% 3 5% 4 3 4 3 4 5% 45%	2514
	11th to 20th	Night	21% 14% 3 5% 3 3 3 4 5% 5% 34%	2730
	21st to end	Night	19% 14% 4 8% 5% 4 5% 3 4 5% 30%	2856
December	1st to 10th	Night	18% 15% 5% 15% 4 3 3 3 4 5% 24%	4720
	11th to 20th	Night	23% 17% 7% 8% 4 4 3 2 3 4 24%	5274
	21st to end	Night	19% 18% 4 9% 5% 5% 4 3 5% 6% 21%	6633

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	73% 3 8% 11% 4	5259
	11th to 20th	Day	72% 2 5% 12% 9%	5280
	21st to end	Day	66% 2 7% 17% 7% 1	5780
February	1st to 10th	Day	64% 4 8% 16% 8%	1890
	11th to 20th	Day	65% 4 7% 15% 9% 1	1906
	21st to end	Day	62% 4 7% 16% 10% 1	1756
March	1st to 10th	Day	54% 3 7% 21% 11% 3	5045
	11th to 20th	Day	44% 4 8% 25% 15% 4	5090
	21st to end	Day	57% 5% 7% 19% 11% 1	5586
April	1st to 10th	Day	52% 5% 10% 17% 13% 3	2372
	11th to 20th	Day	46% 5% 11% 18% 16% 3	2522
	21st to end	Day	51% 6% 10% 19% 12% 1	2730
May	1st to 10th	Day	54% 6% 10% 21% 8% 1	7651
	11th to 20th	Day	50% 7% 10% 24% 9% 1	7630
	21st to end	Day	51% 7% 11% 16% 11% 4	8405
June	1st to 10th	Day	43% 8% 13% 20% 15% 1	2730
	11th to 20th	Day	45% 9% 13% 21% 12% 1	2730
	21st to end	Day	42% 8% 14% 23% 12% 1	2730
July	1st to 10th	Day	39% 8% 12% 24% 15% 2	5965
	11th to 20th	Day	45% 10% 13% 24% 8% 1	5896
	21st to end	Day	48% 7% 12% 18% 15% 1	6240
August	1st to 10th	Day	46% 8% 15% 25% 7%	4221
	11th to 20th	Day	44% 7% 10% 27% 11%	4213
	21st to end	Day	31% 7% 15% 32% 15% 1	4449
September	1st to 10th	Day	39% 6% 10% 19% 22% 4	2332
	11th to 20th	Day	38% 7% 10% 24% 18% 2	2200
	21st to end	Day	48% 5% 9% 21% 15% 1	2200
October	1st to 10th	Day	31% 3 7% 26% 30% 3	3308
	11th to 20th	Day	40% 4 9% 21% 19% 8%	3240
	21st to end	Day	34% 3 9% 29% 20% 5%	3538
November	1st to 10th	Day	42% 4 8% 25% 18% 4	2000
	11th to 20th	Day	50% 5% 8% 18% 16% 4	1890
	21st to end	Day	56% 4 9% 17% 12% 1	1758
December	1st to 10th	Day	68% 3 7% 18% 4 1	2680
	11th to 20th	Day	62% 4 9% 15% 9%	3130
	21st to end	Day	63% 5% 10% 16% 6%	4565
January	1st to 10th	Night	73% 3 8% 13% 3 1	7636
	11th to 20th	Night	73% 3 4 12% 8% 1	7680
	21st to end	Night	64% 3 8% 16% 7% 1	8401
February	1st to 10th	Night	62% 4 9% 15% 9%	2730
	11th to 20th	Night	67% 3 7% 14% 9% 1	2607
	21st to end	Night	62% 4 7% 15% 9% 3	2048
March	1st to 10th	Night	54% 3 6% 23% 12% 2	5028
	11th to 20th	Night	46% 3 7% 23% 18% 3	5090
	21st to end	Night	53% 4 9% 19% 13% 2	5588
April	1st to 10th	Night	53% 4 9% 18% 13% 2	2247
	11th to 20th	Night	44% 5% 13% 19% 14% 4	2065
	21st to end	Night	48% 5% 12% 20% 13% 2	1890
May	1st to 10th	Night	57% 6% 10% 15% 10% 1	5264
	11th to 20th	Night	47% 9% 13% 21% 9% 1	5235
	21st to end	Night	59% 7% 10% 13% 9% 3	5771
June	1st to 10th	Night	41% 8% 13% 22% 15% 1	1890
	11th to 20th	Night	43% 10% 13% 20% 13% 2	1890
	21st to end	Night	37% 9% 14% 24% 14% 1	1890
July	1st to 10th	Night	44% 9% 12% 23% 12% 1	4105
	11th to 20th	Night	46% 8% 16% 22% 7% 1	4051
	21st to end	Night	46% 9% 13% 19% 13% 1	4297
August	1st to 10th	Night	48% 8% 15% 21% 6% 1	2904
	11th to 20th	Night	46% 6% 10% 23% 14% 1	2902
	21st to end	Night	33% 6% 12% 33% 16% 1	3416
September	1st to 10th	Night	39% 6% 14% 19% 18% 4	2063
	11th to 20th	Night	35% 5% 11% 24% 23% 3	2200
	21st to end	Night	44% 6% 11% 21% 17% 1	2200
October	1st to 10th	Night	32% 5% 8% 27% 24% 4	3872
	11th to 20th	Night	39% 4 7% 20% 22% 7%	3899
	21st to end	Night	35% 3 6% 27% 24% 5%	4252
November	1st to 10th	Night	42% 4 9% 18% 20% 6%	2514
	11th to 20th	Night	53% 4 7% 16% 16% 4	2730
	21st to end	Night	57% 5% 7% 17% 13% 2	2856
December	1st to 10th	Night	65% 3 8% 18% 4 1	4720
	11th to 20th	Night	66% 3 8% 15% 7%	5277
	21st to end	Night	65% 4 9% 14% 7%	6633

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	39% 27% 20% 10% 3	330
	11th to 20th	Day	45% 26% 22% 7%	330
	21st to end	Day	42% 24% 24% 7% 2	363
February	1st to 10th	Day	38% 22% 29% 9% 2	330
	11th to 20th	Day	52% 21% 19% 7% 1	330
	21st to end	Day	40% 21% 31% 8%	299
March	1st to 10th	Day	37% 19% 27% 13% 3	540
	11th to 20th	Day	37% 23% 23% 12% 4 1	540
	21st to end	Day	38% 17% 27% 13% 4 1	594
April	1st to 10th	Day	35% 19% 25% 17% 4	540
	11th to 20th	Day	30% 16% 29% 15% 8% 2	532
	21st to end	Day	32% 17% 26% 16% 7% 2	540
May	1st to 10th	Day	34% 16% 28% 12% 8% 3	543
	11th to 20th	Day	27% 13% 27% 20% 9% 3	567
	21st to end	Day	22% 9% 25% 22% 17% 6%	617
June	1st to 10th	Day	17% 11% 25% 26% 15% 6%	570
	11th to 20th	Day	20% 9% 26% 22% 16% 6%	570
	21st to end	Day	15% 11% 27% 26% 16% 5%	570
July	1st to 10th	Day	16% 7% 19% 26% 22% 11%	565
	11th to 20th	Day	13% 6% 22% 33% 18% 9%	544
	21st to end	Day	20% 6% 21% 25% 19% 9%	576
August	1st to 10th	Day	14% 6% 20% 32% 18% 10%	526
	11th to 20th	Day	17% 5% 18% 30% 19% 9%	519
	21st to end	Day	14% 5% 20% 31% 21% 9%	583
September	1st to 10th	Day	16% 7% 16% 28% 23% 9%	530
	11th to 20th	Day	14% 4 15% 34% 24% 9%	530
	21st to end	Day	26% 7% 27% 23% 14% 3	530
October	1st to 10th	Day	19% 8% 24% 24% 18% 6%	530
	11th to 20th	Day	24% 14% 25% 23% 12% 2	530
	21st to end	Day	28% 16% 26% 21% 8% 1	583
November	1st to 10th	Day	24% 13% 29% 24% 9% 2	478
	11th to 20th	Day	38% 15% 26% 15% 6% 1	330
	21st to end	Day	37% 17% 30% 14% 2 1	260
December	1st to 10th	Day	39% 20% 28% 10% 3 1	220
	11th to 20th	Day	38% 16% 27% 13% 5%	234
	21st to end	Day	40% 19% 25% 13% 3	363
January	1st to 10th	Night	38% 19% 26% 13% 4	840
	11th to 20th	Night	39% 18% 24% 18% 1	840
	21st to end	Night	34% 18% 28% 17% 1	924
February	1st to 10th	Night	32% 18% 27% 21% 3	840
	11th to 20th	Night	38% 20% 27% 13% 1	823
	21st to end	Night	38% 17% 29% 15% 1	692
March	1st to 10th	Night	33% 16% 27% 22% 2	840
	11th to 20th	Night	35% 18% 25% 16% 5% 1	840
	21st to end	Night	32% 15% 29% 19% 4	924
April	1st to 10th	Night	30% 15% 30% 20% 4	840
	11th to 20th	Night	22% 13% 30% 25% 9% 1	821
	21st to end	Night	24% 10% 32% 26% 7%	630
May	1st to 10th	Night	26% 11% 28% 25% 9% 1	630
	11th to 20th	Night	24% 7% 26% 32% 10% 1	621
	21st to end	Night	17% 5% 23% 31% 19% 5%	683
June	1st to 10th	Night	15% 5% 20% 38% 20% 2	630
	11th to 20th	Night	15% 4 19% 40% 21% 2	630
	21st to end	Night	17% 3 19% 40% 19% 2	630
July	1st to 10th	Night	15% 5% 10% 39% 26% 5%	615
	11th to 20th	Night	14% 4 13% 37% 27% 5%	597
	21st to end	Night	16% 3 9% 39% 29% 5%	657
August	1st to 10th	Night	15% 4 11% 39% 28% 3	597
	11th to 20th	Night	17% 4 10% 36% 27% 5%	594
	21st to end	Night	13% 3 10% 40% 29% 6%	775
September	1st to 10th	Night	17% 4 15% 34% 27% 4	800
	11th to 20th	Night	15% 4 14% 35% 28% 4	800
	21st to end	Night	19% 6% 23% 29% 21% 2	800
October	1st to 10th	Night	18% 6% 18% 34% 21% 3	800
	11th to 20th	Night	24% 9% 23% 29% 13% 2	800
	21st to end	Night	30% 9% 23% 28% 10% 1	880
November	1st to 10th	Night	21% 10% 24% 30% 14% 1	820
	11th to 20th	Night	33% 13% 25% 21% 7% 1	840
	21st to end	Night	30% 15% 26% 24% 5% 1	840
December	1st to 10th	Night	37% 16% 23% 20% 4	840
	11th to 20th	Night	32% 19% 24% 22% 3	840
	21st to end	Night	34% 15% 27% 22% 2	924

Page generated at 2026-07-13 03:14:49. Version ac07

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