Sioux Falls
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sioux Falls clear sky chart from 2005-11-06 to 2024-11-03.

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% 7% 3 7% 5% 4 4 4 5% 7% 41%	101443
	Night	10% 7% 3 7% 4 4 4 4 5% 7% 44%	97623
Transparency	Day	23% 49% 7% 14% 7% 1	101239
	Night	21% 49% 7% 13% 8% 1	97498
Seeing	Day	15% 11% 32% 28% 12% 2	15938
	Night	13% 9% 35% 33% 10% 1	25799

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% 14% 3 14% 11% 8% 6% 4 4 5% 21%	2414
	11th to 20th	Day	5% 14% 6% 11% 5% 6% 10% 3 8% 10% 22%	2669
	21st to end	Day	7% 13% 7% 14% 9% 8% 7% 5% 4 6% 22%	3135
February	1st to 10th	Day	8% 12% 4 12% 7% 8% 6% 4 5% 6% 27%	1710
	11th to 20th	Day	8% 11% 5% 9% 7% 6% 6% 4 6% 5% 34%	1678
	21st to end	Day	11% 10% 4 8% 5% 6% 5% 4 5% 7% 36%	1570
March	1st to 10th	Day	12% 9% 4 8% 4 3 4 3 4 7% 42%	3312
	11th to 20th	Day	9% 8% 3 8% 4 4 4 3 4 6% 47%	3480
	21st to end	Day	25% 12% 4 11% 4 4 3 3 4 5% 25%	3814
April	1st to 10th	Day	16% 8% 2 7% 5% 4 4 4 5% 7% 38%	2152
	11th to 20th	Day	19% 8% 3 6% 4 4 4 3 5% 6% 37%	2442
	21st to end	Day	21% 8% 2 6% 4 3 4 3 5% 6% 37%	2470
May	1st to 10th	Day	17% 6% 3 6% 4 4 5% 4 7% 8% 36%	4082
	11th to 20th	Day	13% 6% 2 6% 4 4 4 3 5% 6% 48%	4082
	21st to end	Day	18% 7% 2 6% 4 4 4 3 5% 7% 40%	4820
June	1st to 10th	Day	12% 5% 2 5% 3 4 4 3 6% 8% 48%	2753
	11th to 20th	Day	14% 6% 2 5% 4 4 4 4 6% 7% 44%	2850
	21st to end	Day	9% 5% 2 5% 4 4 4 4 7% 9% 48%	2850
July	1st to 10th	Day	10% 5% 2 7% 4 5% 5% 5% 7% 9% 41%	4750
	11th to 20th	Day	7% 3 1 4 3 3 4 4 5% 7% 59%	4363
	21st to end	Day	4 3 2 4 4 4 5% 5% 7% 10% 52%	4465
August	1st to 10th	Day	8% 5% 3 6% 4 5% 5% 5% 7% 9% 45%	4104
	11th to 20th	Day	16% 7% 2 7% 4 4 5% 4 7% 8% 36%	4041
	21st to end	Day	9% 4 2 6% 4 4 4 3 5% 8% 52%	4532
September	1st to 10th	Day	14% 5% 1 4 3 3 3 3 4 6% 53%	2215
	11th to 20th	Day	11% 5% 2 5% 3 3 3 3 4 7% 55%	2090
	21st to end	Day	10% 4 2 4 5% 3 3 3 6% 7% 53%	2090
October	1st to 10th	Day	16% 7% 1 5% 3 3 3 3 5% 6% 48%	1955
	11th to 20th	Day	13% 7% 2 5% 3 3 4 2 4 5% 53%	1900
	21st to end	Day	15% 8% 3 6% 3 3 3 3 4 6% 46%	2012
November	1st to 10th	Day	10% 7% 3 5% 4 4 3 3 7% 8% 46%	1691
	11th to 20th	Day	9% 8% 2 12% 6% 5% 4 3 4 5% 40%	1566
	21st to end	Day	11% 9% 3 7% 4 4 5% 4 5% 7% 41%	1520
December	1st to 10th	Day	7% 10% 3 11% 6% 5% 5% 3 7% 8% 35%	1520
	11th to 20th	Day	7% 12% 4 11% 7% 7% 6% 4 5% 7% 30%	1904
	21st to end	Day	17% 8% 4 16% 7% 3 4 3 6% 7% 25%	2442
January	1st to 10th	Night	10% 12% 4 13% 10% 6% 5% 4 5% 6% 25%	4536
	11th to 20th	Night	4 10% 4 11% 7% 6% 8% 6% 9% 8% 27%	4296
	21st to end	Night	6% 11% 7% 13% 5% 7% 6% 5% 6% 7% 28%	4532
February	1st to 10th	Night	9% 11% 3 10% 6% 5% 4 4 5% 6% 37%	2470
	11th to 20th	Night	8% 10% 4 8% 6% 4 5% 3 5% 7% 41%	2403
	21st to end	Night	8% 9% 3 8% 6% 5% 4 5% 6% 7% 42%	1887
March	1st to 10th	Night	8% 7% 2 6% 4 3 3 3 5% 7% 51%	3545
	11th to 20th	Night	9% 7% 2 6% 4 4 4 4 5% 7% 49%	3480
	21st to end	Night	24% 12% 3 7% 6% 4 4 3 4 6% 27%	3817
April	1st to 10th	Night	14% 8% 3 6% 4 4 4 5% 5% 7% 40%	2025
	11th to 20th	Night	18% 8% 2 6% 4 3 4 2 4 6% 44%	1689
	21st to end	Night	16% 8% 3 5% 4 3 5% 3 6% 6% 41%	1710
May	1st to 10th	Night	17% 6% 2 4 3 3 3 3 6% 6% 46%	2823
	11th to 20th	Night	9% 5% 3 5% 3 4 4 4 5% 7% 51%	2823
	21st to end	Night	16% 6% 2 6% 4 4 3 3 6% 8% 44%	2744
June	1st to 10th	Night	7% 5% 2 5% 3 3 5% 3 6% 7% 55%	1421
	11th to 20th	Night	7% 4 1 5% 4 4 4 3 7% 8% 52%	1330
	21st to end	Night	7% 4 1 3 4 3 3 4 5% 8% 57%	1330
July	1st to 10th	Night	9% 5% 2 5% 3 3 4 4 5% 9% 51%	2220
	11th to 20th	Night	5% 2 1 3 3 3 3 3 5% 6% 66%	2589
	21st to end	Night	3 3 1 3 3 3 4 3 7% 10% 59%	3098
August	1st to 10th	Night	6% 6% 2 5% 4 5% 6% 5% 6% 8% 48%	2836
	11th to 20th	Night	12% 5% 2 4 4 4 3 3 5% 8% 50%	2798
	21st to end	Night	8% 3 1 5% 3 3 3 4 6% 8% 55%	3135
September	1st to 10th	Night	8% 3 1 4 3 2 3 3 5% 6% 59%	1960
	11th to 20th	Night	8% 5% 2 4 3 3 4 3 5% 7% 57%	2090
	21st to end	Night	9% 4 2 3 3 2 3 3 5% 6% 59%	2090
October	1st to 10th	Night	15% 5% 1 4 3 2 3 3 4 6% 54%	2205
	11th to 20th	Night	12% 6% 2 5% 3 3 3 3 4 6% 53%	2280
	21st to end	Night	13% 8% 2 6% 3 3 3 2 4 7% 49%	2584
November	1st to 10th	Night	9% 5% 2 5% 4 4 4 3 5% 7% 52%	2432
	11th to 20th	Night	9% 6% 2 8% 4 3 4 4 6% 8% 44%	2612
	21st to end	Night	9% 8% 2 7% 4 4 3 3 5% 7% 47%	2660
December	1st to 10th	Night	8% 9% 4 9% 5% 4 5% 4 6% 7% 39%	2660
	11th to 20th	Night	9% 9% 3 7% 5% 5% 4 4 5% 8% 39%	3288
	21st to end	Night	17% 10% 4 14% 5% 4 4 3 4 5% 28%	5225

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	47% 37% 6% 7% 3	2415
	11th to 20th	Day	36% 37% 5% 18% 4	2669
	21st to end	Day	37% 43% 9% 7% 4	3135
February	1st to 10th	Day	21% 66% 4 4 5%	1710
	11th to 20th	Day	18% 65% 4 9% 4 1	1687
	21st to end	Day	17% 65% 3 7% 8%	1570
March	1st to 10th	Day	23% 42% 7% 21% 7% 1	3312
	11th to 20th	Day	19% 41% 4 21% 11% 3	3480
	21st to end	Day	40% 42% 9% 8% 2	3814
April	1st to 10th	Day	17% 65% 5% 8% 3 1	2152
	11th to 20th	Day	17% 66% 4 9% 3 1	2442
	21st to end	Day	18% 65% 3 8% 5%	2470
May	1st to 10th	Day	23% 43% 8% 16% 9%	4120
	11th to 20th	Day	21% 41% 6% 18% 11% 3	4086
	21st to end	Day	25% 42% 6% 15% 11%	4833
June	1st to 10th	Day	9% 66% 6% 12% 6% 1	2753
	11th to 20th	Day	16% 66% 5% 9% 4	2850
	21st to end	Day	13% 64% 6% 12% 4 1	2850
July	1st to 10th	Day	28% 39% 13% 13% 6% 1	4676
	11th to 20th	Day	16% 38% 9% 26% 11%	4287
	21st to end	Day	17% 38% 13% 18% 14% 1	4325
August	1st to 10th	Day	24% 39% 8% 20% 9%	4090
	11th to 20th	Day	33% 39% 9% 15% 3	4080
	21st to end	Day	23% 40% 14% 16% 7%	4531
September	1st to 10th	Day	15% 60% 5% 15% 5%	2215
	11th to 20th	Day	11% 60% 8% 15% 6%	2090
	21st to end	Day	15% 61% 4 11% 8% 1	2090
October	1st to 10th	Day	17% 60% 5% 12% 5%	1955
	11th to 20th	Day	12% 59% 4 13% 10% 1	1900
	21st to end	Day	19% 58% 5% 10% 8%	2012
November	1st to 10th	Day	19% 59% 6% 10% 6%	1691
	11th to 20th	Day	18% 59% 5% 12% 6%	1566
	21st to end	Day	21% 60% 5% 8% 6%	1520
December	1st to 10th	Day	18% 60% 7% 9% 5% 1	1520
	11th to 20th	Day	26% 49% 10% 12% 2	1901
	21st to end	Day	38% 37% 9% 11% 5% 1	2442
January	1st to 10th	Night	43% 38% 6% 10% 4	4536
	11th to 20th	Night	31% 38% 8% 14% 8% 1	4296
	21st to end	Night	33% 43% 10% 8% 5%	4532
February	1st to 10th	Night	18% 65% 5% 6% 5%	2470
	11th to 20th	Night	18% 64% 4 9% 5% 1	2404
	21st to end	Night	13% 65% 4 8% 8% 2	1887
March	1st to 10th	Night	16% 42% 6% 19% 16% 1	3545
	11th to 20th	Night	17% 41% 7% 20% 13% 2	3480
	21st to end	Night	40% 42% 8% 8% 2	3817
April	1st to 10th	Night	16% 66% 5% 9% 4	2025
	11th to 20th	Night	15% 66% 4 7% 7% 1	1689
	21st to end	Night	16% 65% 3 9% 7% 1	1710
May	1st to 10th	Night	24% 42% 7% 13% 13% 2	2850
	11th to 20th	Night	17% 43% 7% 17% 14% 3	2824
	21st to end	Night	22% 42% 6% 19% 11%	2752
June	1st to 10th	Night	7% 65% 6% 10% 9% 2	1421
	11th to 20th	Night	12% 65% 5% 11% 6% 1	1330
	21st to end	Night	9% 64% 7% 12% 6% 1	1330
July	1st to 10th	Night	23% 37% 15% 16% 7% 2	2185
	11th to 20th	Night	13% 36% 9% 28% 12% 1	2542
	21st to end	Night	12% 39% 13% 21% 13% 2	2999
August	1st to 10th	Night	24% 39% 9% 17% 10% 1	2826
	11th to 20th	Night	25% 40% 12% 17% 5%	2825
	21st to end	Night	20% 40% 12% 16% 11%	3135
September	1st to 10th	Night	11% 60% 7% 13% 9% 1	1960
	11th to 20th	Night	9% 60% 7% 15% 7% 1	2090
	21st to end	Night	13% 60% 6% 11% 9% 1	2090
October	1st to 10th	Night	14% 60% 5% 13% 8%	2205
	11th to 20th	Night	11% 60% 4 13% 11% 2	2280
	21st to end	Night	16% 59% 6% 11% 8%	2584
November	1st to 10th	Night	16% 58% 6% 12% 7%	2432
	11th to 20th	Night	13% 60% 6% 14% 7% 1	2612
	21st to end	Night	17% 60% 5% 12% 6%	2660
December	1st to 10th	Night	18% 60% 7% 10% 5%	2660
	11th to 20th	Night	19% 50% 13% 13% 4	3290
	21st to end	Night	39% 38% 5% 12% 5%	5225

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	16% 10% 37% 25% 10% 2	270
	11th to 20th	Day	18% 13% 35% 28% 6% 1	270
	21st to end	Day	16% 11% 38% 24% 10% 1	297
February	1st to 10th	Day	13% 18% 40% 27% 3	270
	11th to 20th	Day	13% 17% 41% 22% 7%	270
	21st to end	Day	16% 16% 44% 21% 2	225
March	1st to 10th	Day	19% 16% 41% 18% 5% 1	270
	11th to 20th	Day	20% 13% 37% 21% 8% 1	270
	21st to end	Day	27% 14% 32% 20% 6% 1	297
April	1st to 10th	Day	23% 19% 38% 17% 3	332
	11th to 20th	Day	26% 15% 32% 22% 5% 1	640
	21st to end	Day	26% 16% 27% 20% 9% 2	650
May	1st to 10th	Day	22% 12% 32% 25% 8% 1	653
	11th to 20th	Day	21% 11% 29% 25% 11% 3	675
	21st to end	Day	19% 10% 29% 30% 11% 1	734
June	1st to 10th	Day	9% 9% 25% 34% 20% 3	680
	11th to 20th	Day	14% 8% 35% 28% 11% 3	680
	21st to end	Day	11% 6% 34% 32% 15% 1	680
July	1st to 10th	Day	7% 3 22% 39% 23% 5%	671
	11th to 20th	Day	6% 6% 30% 36% 18% 3	668
	21st to end	Day	5% 3 26% 41% 21% 4	739
August	1st to 10th	Day	10% 4 24% 38% 21% 4	676
	11th to 20th	Day	12% 4 26% 33% 22% 3	665
	21st to end	Day	8% 6% 28% 36% 18% 4	748
September	1st to 10th	Day	15% 8% 27% 30% 17% 3	425
	11th to 20th	Day	10% 7% 34% 34% 13% 3	300
	21st to end	Day	12% 17% 31% 26% 10% 4	300
October	1st to 10th	Day	19% 11% 30% 25% 10% 5%	300
	11th to 20th	Day	13% 19% 35% 25% 8%	300
	21st to end	Day	22% 17% 35% 19% 6% 1	330
November	1st to 10th	Day	19% 12% 36% 23% 7% 3	276
	11th to 20th	Day	14% 19% 43% 17% 7%	270
	21st to end	Day	20% 17% 33% 23% 8%	270
December	1st to 10th	Day	10% 13% 44% 22% 10% 1	270
	11th to 20th	Day	15% 14% 40% 27% 4	270
	21st to end	Day	21% 14% 40% 22% 3	297
January	1st to 10th	Night	11% 11% 39% 30% 9% 1	950
	11th to 20th	Night	12% 12% 37% 31% 6% 1	950
	21st to end	Night	15% 10% 39% 28% 7%	1045
February	1st to 10th	Night	13% 12% 40% 29% 6% 1	950
	11th to 20th	Night	12% 12% 40% 30% 5% 1	929
	21st to end	Night	13% 8% 40% 30% 8% 1	631
March	1st to 10th	Night	14% 10% 42% 28% 6% 1	649
	11th to 20th	Night	15% 12% 38% 31% 4	570
	21st to end	Night	19% 11% 34% 27% 8% 1	627
April	1st to 10th	Night	19% 13% 38% 27% 4	570
	11th to 20th	Night	22% 15% 31% 26% 6% 1	563
	21st to end	Night	19% 13% 33% 25% 9% 1	570
May	1st to 10th	Night	18% 9% 35% 29% 8%	570
	11th to 20th	Night	16% 9% 34% 31% 9% 1	561
	21st to end	Night	17% 6% 32% 32% 12%	617
June	1st to 10th	Night	9% 7% 28% 38% 17% 1	570
	11th to 20th	Night	8% 4 37% 39% 10% 1	570
	21st to end	Night	8% 5% 25% 48% 14%	570
July	1st to 10th	Night	7% 2 23% 43% 25% 1	555
	11th to 20th	Night	4 2 27% 49% 18%	552
	21st to end	Night	4 2 24% 51% 18% 1	624
August	1st to 10th	Night	7% 3 25% 45% 20% 1	567
	11th to 20th	Night	9% 3 23% 40% 24% 1	564
	21st to end	Night	6% 4 29% 41% 19% 1	627
September	1st to 10th	Night	9% 4 28% 42% 15% 2	570
	11th to 20th	Night	9% 6% 33% 35% 14% 2	570
	21st to end	Night	12% 7% 34% 34% 12% 1	570
October	1st to 10th	Night	16% 9% 35% 28% 12% 1	685
	11th to 20th	Night	16% 12% 36% 29% 7%	760
	21st to end	Night	17% 12% 34% 28% 9%	912
November	1st to 10th	Night	12% 9% 38% 32% 9% 1	936
	11th to 20th	Night	13% 12% 39% 29% 7% 1	950
	21st to end	Night	13% 11% 38% 31% 7%	950
December	1st to 10th	Night	13% 11% 38% 31% 6%	950
	11th to 20th	Night	16% 8% 39% 29% 7%	950
	21st to end	Night	21% 12% 36% 26% 6%	1045

Page generated at 2024-10-31 02:39:27. Version ac07

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