Sioux City
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sioux City clear sky chart from 2005-11-06 to 2024-01-13.

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 6% 5% 3 4 4 5% 7% 43%	75113
	Night	11% 7% 3 6% 5% 3 4 4 5% 7% 46%	74648
Transparency	Day	40% 6% 13% 25% 13% 2	74827
	Night	38% 6% 13% 26% 15% 2	74454
Seeing	Day	15% 9% 31% 29% 13% 2	14704
	Night	14% 9% 34% 33% 10% 1	24726

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	8% 10% 5% 8% 8% 5% 6% 5% 5% 5% 35%	1683
	11th to 20th	Day	9% 12% 5% 9% 7% 3 5% 5% 5% 8% 32%	1643
	21st to end	Day	11% 12% 5% 11% 8% 4 6% 6% 6% 6% 26%	1782
February	1st to 10th	Day	11% 9% 5% 10% 9% 5% 6% 5% 5% 7% 28%	1620
	11th to 20th	Day	10% 10% 4 7% 6% 3 3 5% 4 5% 40%	1592
	21st to end	Day	13% 10% 4 7% 6% 4 6% 4 6% 6% 34%	1480
March	1st to 10th	Day	13% 10% 5% 7% 5% 3 3 3 4 6% 41%	1926
	11th to 20th	Day	14% 10% 4 7% 6% 3 4 3 5% 8% 36%	1980
	21st to end	Day	19% 12% 5% 6% 6% 4 4 4 5% 6% 30%	2178
April	1st to 10th	Day	15% 8% 4 6% 5% 3 5% 4 5% 6% 38%	2034
	11th to 20th	Day	19% 9% 3 5% 5% 3 3 4 4 7% 37%	2280
	21st to end	Day	21% 8% 3 5% 5% 3 4 5% 4 5% 37%	2340
May	1st to 10th	Day	17% 7% 3 6% 5% 3 4 4 5% 7% 37%	2340
	11th to 20th	Day	16% 7% 2 5% 6% 3 4 4 5% 7% 40%	2302
	21st to end	Day	17% 7% 3 6% 6% 3 5% 5% 5% 7% 37%	2679
June	1st to 10th	Day	10% 4 2 4 5% 3 4 4 6% 9% 49%	2520
	11th to 20th	Day	11% 5% 3 4 4 3 5% 5% 6% 8% 46%	2636
	21st to end	Day	8% 4 2 6% 5% 3 5% 5% 5% 9% 49%	2700
July	1st to 10th	Day	6% 4 2 4 4 3 4 6% 6% 10% 52%	2652
	11th to 20th	Day	7% 4 2 3 3 2 5% 4 5% 7% 58%	2350
	21st to end	Day	6% 3 2 4 4 4 4 5% 7% 9% 53%	2546
August	1st to 10th	Day	11% 5% 2 5% 5% 3 6% 5% 7% 8% 41%	2328
	11th to 20th	Day	11% 4 2 4 4 3 3 5% 5% 8% 50%	2301
	21st to end	Day	8% 5% 2 4 4 2 4 4 6% 8% 54%	2561
September	1st to 10th	Day	15% 5% 2 4 4 3 4 4 3 6% 51%	2093
	11th to 20th	Day	10% 5% 2 4 4 2 4 3 5% 7% 54%	1980
	21st to end	Day	11% 4 2 4 4 3 3 4 5% 5% 55%	1980
October	1st to 10th	Day	15% 6% 2 4 4 2 4 3 4 5% 48%	1846
	11th to 20th	Day	14% 6% 2 4 4 1 3 4 4 4 55%	1800
	21st to end	Day	16% 7% 3 6% 5% 2 4 2 4 4 47%	1951
November	1st to 10th	Day	10% 6% 3 4 4 2 3 4 5% 7% 51%	1673
	11th to 20th	Day	9% 8% 2 8% 6% 3 4 4 5% 7% 44%	1596
	21st to end	Day	13% 9% 4 5% 3 2 3 4 5% 8% 43%	1520
December	1st to 10th	Day	9% 7% 5% 9% 6% 3 4 4 5% 8% 39%	1520
	11th to 20th	Day	8% 11% 4 7% 7% 4 6% 6% 7% 6% 33%	1918
	21st to end	Day	17% 9% 4 15% 7% 4 5% 4 5% 6% 24%	2783
January	1st to 10th	Night	8% 7% 3 7% 8% 4 6% 6% 5% 7% 38%	2477
	11th to 20th	Night	8% 11% 4 9% 7% 4 4 4 6% 7% 36%	2379
	21st to end	Night	11% 11% 4 8% 6% 3 5% 5% 5% 8% 34%	2574
February	1st to 10th	Night	11% 9% 4 9% 6% 3 5% 4 4 6% 39%	2340
	11th to 20th	Night	9% 9% 5% 6% 6% 2 4 4 6% 7% 42%	2272
	21st to end	Night	9% 9% 4 6% 5% 3 5% 5% 5% 6% 43%	1776
March	1st to 10th	Night	11% 7% 4 6% 4 3 4 5% 4 6% 45%	2033
	11th to 20th	Night	14% 9% 4 6% 4 2 3 4 5% 7% 42%	1980
	21st to end	Night	16% 10% 4 6% 6% 3 5% 5% 5% 6% 34%	2178
April	1st to 10th	Night	15% 6% 3 5% 5% 3 5% 5% 5% 6% 42%	1925
	11th to 20th	Night	14% 7% 3 6% 4 4 4 4 4 7% 44%	1629
	21st to end	Night	16% 6% 3 5% 5% 3 4 5% 4 5% 42%	1620
May	1st to 10th	Night	15% 6% 3 4 3 3 4 4 5% 7% 45%	1620
	11th to 20th	Night	14% 5% 2 4 4 3 4 4 5% 7% 49%	1593
	21st to end	Night	14% 5% 3 6% 5% 3 4 5% 5% 8% 41%	1595
June	1st to 10th	Night	8% 3 2 4 4 3 4 5% 6% 9% 53%	1440
	11th to 20th	Night	7% 4 2 4 4 3 4 5% 4 9% 54%	1317
	21st to end	Night	5% 3 1 5% 4 3 3 4 5% 8% 58%	1260
July	1st to 10th	Night	6% 3 1 3 4 4 4 3 6% 8% 59%	1304
	11th to 20th	Night	3 1 1 3 4 3 4 4 6% 8% 64%	1606
	21st to end	Night	3 2 2 4 4 2 5% 4 6% 8% 60%	1772
August	1st to 10th	Night	8% 4 3 4 4 2 4 6% 5% 8% 51%	1611
	11th to 20th	Night	9% 4 2 3 3 2 2 4 4 6% 60%	1600
	21st to end	Night	7% 3 2 3 4 3 4 5% 5% 8% 57%	1795
September	1st to 10th	Night	10% 3 2 5% 4 3 3 3 5% 6% 58%	1863
	11th to 20th	Night	9% 4 2 3 3 2 4 4 5% 6% 57%	1980
	21st to end	Night	10% 3 2 4 3 2 3 3 4 6% 61%	1980
October	1st to 10th	Night	15% 5% 2 4 3 2 4 3 5% 6% 50%	2095
	11th to 20th	Night	15% 6% 2 4 4 2 4 3 3 5% 53%	2160
	21st to end	Night	15% 7% 2 5% 3 2 3 3 4 5% 51%	2402
November	1st to 10th	Night	7% 5% 2 4 4 2 4 4 4 8% 55%	2405
	11th to 20th	Night	10% 6% 3 7% 5% 3 4 4 5% 7% 48%	2584
	21st to end	Night	10% 8% 3 5% 4 3 4 4 4 6% 50%	2660
December	1st to 10th	Night	8% 8% 4 8% 6% 3 4 5% 4 7% 42%	2660
	11th to 20th	Night	9% 9% 4 6% 6% 4 4 4 5% 7% 42%	3279
	21st to end	Night	17% 11% 5% 12% 6% 4 4 4 4 4 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	50% 6% 16% 19% 8% 1	1684
	11th to 20th	Day	50% 6% 15% 20% 8%	1643
	21st to end	Day	56% 7% 14% 16% 6%	1782
February	1st to 10th	Day	54% 6% 14% 15% 10% 1	1620
	11th to 20th	Day	46% 5% 14% 22% 12% 2	1601
	21st to end	Day	49% 8% 11% 19% 11% 2	1480
March	1st to 10th	Day	46% 4 13% 25% 10% 2	1926
	11th to 20th	Day	49% 5% 11% 24% 10% 1	1980
	21st to end	Day	55% 6% 14% 18% 6% 1	2178
April	1st to 10th	Day	46% 6% 13% 23% 11% 1	2034
	11th to 20th	Day	48% 5% 11% 21% 13% 2	2280
	21st to end	Day	48% 5% 10% 25% 12%	2340
May	1st to 10th	Day	46% 7% 13% 22% 12% 1	2340
	11th to 20th	Day	43% 8% 13% 24% 11% 1	2306
	21st to end	Day	46% 7% 13% 21% 12% 1	2679
June	1st to 10th	Day	32% 7% 16% 28% 15% 2	2520
	11th to 20th	Day	34% 7% 13% 26% 16% 3	2636
	21st to end	Day	31% 7% 14% 30% 14% 3	2700
July	1st to 10th	Day	27% 8% 18% 31% 15% 2	2580
	11th to 20th	Day	26% 7% 14% 29% 19% 6%	2280
	21st to end	Day	24% 8% 15% 32% 18% 3	2405
August	1st to 10th	Day	38% 9% 14% 26% 12% 1	2314
	11th to 20th	Day	31% 7% 14% 33% 14% 1	2301
	21st to end	Day	28% 7% 12% 27% 20% 4	2561
September	1st to 10th	Day	35% 6% 10% 28% 20% 3	2093
	11th to 20th	Day	31% 5% 13% 32% 17% 2	1980
	21st to end	Day	30% 6% 11% 31% 20% 2	1980
October	1st to 10th	Day	37% 5% 10% 28% 18% 2	1846
	11th to 20th	Day	32% 5% 11% 30% 19% 4	1800
	21st to end	Day	41% 5% 11% 22% 17% 3	1951
November	1st to 10th	Day	33% 5% 16% 26% 18% 2	1673
	11th to 20th	Day	40% 6% 14% 25% 14% 1	1596
	21st to end	Day	41% 4 15% 26% 13% 1	1520
December	1st to 10th	Day	44% 6% 16% 23% 10% 2	1520
	11th to 20th	Day	48% 7% 17% 24% 4	1915
	21st to end	Day	60% 6% 11% 16% 7% 1	2783
January	1st to 10th	Night	44% 7% 13% 23% 12%	2477
	11th to 20th	Night	47% 6% 17% 23% 6%	2379
	21st to end	Night	47% 8% 14% 20% 10% 1	2574
February	1st to 10th	Night	48% 5% 11% 24% 11% 1	2340
	11th to 20th	Night	42% 6% 14% 22% 13% 3	2273
	21st to end	Night	40% 6% 13% 23% 15% 3	1776
March	1st to 10th	Night	40% 6% 13% 30% 9% 2	2033
	11th to 20th	Night	44% 6% 10% 24% 15% 2	1980
	21st to end	Night	50% 7% 14% 20% 7% 2	2178
April	1st to 10th	Night	42% 7% 11% 23% 15% 1	1925
	11th to 20th	Night	42% 4 11% 25% 17% 2	1629
	21st to end	Night	43% 6% 12% 24% 13% 2	1620
May	1st to 10th	Night	38% 7% 13% 24% 15% 2	1620
	11th to 20th	Night	36% 7% 14% 24% 18% 1	1594
	21st to end	Night	41% 7% 15% 21% 12% 3	1596
June	1st to 10th	Night	26% 7% 15% 32% 16% 3	1440
	11th to 20th	Night	28% 6% 14% 27% 21% 4	1317
	21st to end	Night	24% 6% 16% 31% 19% 3	1260
July	1st to 10th	Night	23% 6% 17% 30% 20% 4	1267
	11th to 20th	Night	19% 6% 16% 32% 21% 6%	1553
	21st to end	Night	20% 7% 17% 30% 22% 4	1673
August	1st to 10th	Night	30% 8% 15% 29% 17% 2	1601
	11th to 20th	Night	25% 6% 13% 34% 18% 4	1600
	21st to end	Night	25% 7% 13% 26% 22% 7%	1795
September	1st to 10th	Night	28% 5% 11% 29% 22% 5%	1863
	11th to 20th	Night	26% 7% 13% 33% 20% 2	1980
	21st to end	Night	26% 4 10% 35% 22% 3	1980
October	1st to 10th	Night	35% 5% 10% 26% 22% 2	2095
	11th to 20th	Night	35% 4 8% 27% 23% 4	2160
	21st to end	Night	37% 3 14% 23% 22% 1	2402
November	1st to 10th	Night	29% 5% 15% 25% 22% 4	2405
	11th to 20th	Night	36% 5% 14% 26% 17% 2	2584
	21st to end	Night	37% 5% 12% 29% 16% 1	2660
December	1st to 10th	Night	42% 6% 14% 27% 11% 1	2660
	11th to 20th	Night	42% 4 18% 29% 6% 1	3281
	21st to end	Night	58% 6% 10% 19% 7%	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	17% 16% 31% 25% 10%	270
	11th to 20th	Day	21% 10% 35% 28% 5% 1	248
	21st to end	Day	19% 9% 41% 23% 6% 1	264
February	1st to 10th	Day	15% 16% 39% 28% 3	240
	11th to 20th	Day	16% 14% 41% 23% 5%	240
	21st to end	Day	22% 11% 42% 21% 5%	198
March	1st to 10th	Day	15% 15% 45% 20% 4 1	240
	11th to 20th	Day	26% 13% 38% 15% 8%	240
	21st to end	Day	31% 14% 36% 16% 3 1	264
April	1st to 10th	Day	22% 13% 40% 20% 3 1	294
	11th to 20th	Day	24% 14% 33% 22% 7%	558
	21st to end	Day	26% 12% 31% 22% 8% 2	600
May	1st to 10th	Day	23% 12% 30% 23% 9% 2	603
	11th to 20th	Day	20% 11% 30% 25% 11% 3	625
	21st to end	Day	20% 8% 30% 27% 13% 3	679
June	1st to 10th	Day	8% 7% 24% 36% 21% 4	630
	11th to 20th	Day	11% 6% 34% 32% 15% 2	630
	21st to end	Day	9% 8% 32% 33% 16% 2	630
July	1st to 10th	Day	7% 3 20% 38% 26% 6%	621
	11th to 20th	Day	7% 5% 24% 39% 21% 4	618
	21st to end	Day	5% 3 26% 39% 23% 3	684
August	1st to 10th	Day	11% 4 19% 36% 25% 4	626
	11th to 20th	Day	11% 5% 24% 35% 22% 4	615
	21st to end	Day	9% 4 26% 37% 19% 5%	680
September	1st to 10th	Day	17% 5% 25% 34% 14% 4	383
	11th to 20th	Day	10% 4 36% 31% 15% 4	270
	21st to end	Day	16% 10% 34% 27% 10% 3	270
October	1st to 10th	Day	19% 13% 30% 24% 11% 4	270
	11th to 20th	Day	16% 16% 38% 21% 8%	270
	21st to end	Day	19% 16% 36% 24% 5%	297
November	1st to 10th	Day	17% 16% 34% 24% 7% 3	270
	11th to 20th	Day	16% 20% 38% 23% 3	270
	21st to end	Day	23% 14% 26% 24% 11% 1	270
December	1st to 10th	Day	11% 13% 41% 24% 9% 1	270
	11th to 20th	Day	13% 16% 37% 29% 4	270
	21st to end	Day	23% 12% 40% 22% 2	297
January	1st to 10th	Night	13% 12% 37% 31% 7% 1	950
	11th to 20th	Night	14% 13% 36% 30% 6% 1	915
	21st to end	Night	16% 11% 40% 26% 6%	990
February	1st to 10th	Night	16% 12% 38% 29% 5% 1	900
	11th to 20th	Night	14% 12% 42% 26% 6% 1	878
	21st to end	Night	15% 9% 41% 28% 7% 1	592
March	1st to 10th	Night	14% 10% 39% 30% 7%	593
	11th to 20th	Night	20% 9% 36% 30% 6%	540
	21st to end	Night	21% 12% 35% 26% 6%	594
April	1st to 10th	Night	19% 14% 38% 26% 3	540
	11th to 20th	Night	19% 14% 36% 25% 4 1	533
	21st to end	Night	18% 12% 34% 27% 8% 1	540
May	1st to 10th	Night	18% 10% 32% 31% 9%	540
	11th to 20th	Night	16% 9% 30% 33% 11% 1	531
	21st to end	Night	18% 5% 31% 35% 10% 1	584
June	1st to 10th	Night	7% 5% 26% 46% 15%	540
	11th to 20th	Night	8% 5% 34% 40% 13%	540
	21st to end	Night	6% 4 29% 46% 15%	540
July	1st to 10th	Night	7% 2 18% 45% 28% 1	525
	11th to 20th	Night	4 1 24% 48% 21% 2	522
	21st to end	Night	3 2 19% 55% 20% 1	591
August	1st to 10th	Night	7% 4 20% 46% 22% 1	537
	11th to 20th	Night	9% 4 21% 43% 22% 1	534
	21st to end	Night	7% 3 27% 41% 19% 3	594
September	1st to 10th	Night	10% 6% 25% 40% 18% 1	540
	11th to 20th	Night	10% 4 33% 38% 14% 2	540
	21st to end	Night	11% 7% 34% 35% 12% 1	540
October	1st to 10th	Night	17% 8% 31% 31% 12% 1	655
	11th to 20th	Night	18% 12% 34% 30% 6%	720
	21st to end	Night	18% 13% 29% 29% 11%	818
November	1st to 10th	Night	9% 12% 37% 32% 8% 1	925
	11th to 20th	Night	13% 12% 40% 28% 7%	950
	21st to end	Night	15% 12% 37% 29% 8%	950
December	1st to 10th	Night	13% 11% 39% 30% 7%	950
	11th to 20th	Night	16% 8% 36% 32% 7%	950
	21st to end	Night	21% 12% 36% 25% 5%	1045

Page generated at 2024-01-10 18:35:21. Version ac07

Copyright 2024 Attilla Danko