Dubuque
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Dubuque clear sky chart from 2005-11-06 to 2024-12-09.

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% 9% 3 8% 5% 4 4 4 6% 7% 38%	101805
	Night	13% 9% 3 8% 5% 4 4 3 5% 6% 39%	98074
Transparency	Day	43% 7% 12% 23% 13% 1	105361
	Night	44% 6% 12% 23% 14% 2	102658
Seeing	Day	16% 12% 30% 25% 13% 4	15987
	Night	17% 10% 32% 29% 11% 1	25875

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% 13% 9% 17% 6% 5% 3 3 3 4 26%	2527
	11th to 20th	Day	10% 12% 4 14% 8% 5% 6% 8% 8% 5% 20%	2530
	21st to end	Day	16% 20% 8% 13% 5% 3 3 2 5% 6% 20%	3075
February	1st to 10th	Day	11% 14% 5% 9% 5% 4 5% 5% 5% 6% 31%	1710
	11th to 20th	Day	14% 11% 3 7% 5% 4 4 3 5% 8% 37%	1730
	21st to end	Day	14% 11% 3 10% 5% 3 4 3 4 7% 34%	1570
March	1st to 10th	Day	15% 8% 3 7% 4 4 3 3 4 5% 43%	3142
	11th to 20th	Day	11% 7% 3 7% 5% 4 4 4 5% 7% 43%	3480
	21st to end	Day	20% 14% 4 12% 6% 4 4 4 5% 5% 22%	4025
April	1st to 10th	Day	17% 13% 4 7% 5% 4 4 3 5% 6% 32%	2280
	11th to 20th	Day	15% 12% 3 9% 4 4 5% 4 5% 6% 34%	2254
	21st to end	Day	20% 10% 2 8% 4 4 4 3 5% 6% 34%	2280
May	1st to 10th	Day	16% 9% 3 8% 5% 4 5% 4 6% 6% 35%	4297
	11th to 20th	Day	13% 9% 3 7% 5% 5% 4 4 5% 7% 40%	4399
	21st to end	Day	13% 8% 2 7% 5% 5% 5% 4 6% 8% 39%	4824
June	1st to 10th	Day	11% 6% 2 6% 5% 5% 5% 4 6% 8% 43%	2660
	11th to 20th	Day	10% 7% 3 7% 4 4 4 4 6% 8% 43%	2660
	21st to end	Day	11% 7% 2 7% 4 5% 5% 5% 6% 9% 38%	2660
July	1st to 10th	Day	9% 7% 4 8% 5% 5% 6% 5% 8% 10% 34%	4440
	11th to 20th	Day	5% 3 2 5% 4 4 4 4 7% 10% 52%	4440
	21st to end	Day	7% 6% 2 7% 5% 5% 5% 5% 8% 10% 40%	4813
August	1st to 10th	Day	9% 5% 2 6% 5% 5% 5% 5% 7% 8% 41%	4168
	11th to 20th	Day	10% 5% 3 5% 4 4 5% 4 7% 9% 45%	3896
	21st to end	Day	8% 5% 2 6% 4 3 4 4 7% 8% 48%	4180
September	1st to 10th	Day	13% 6% 2 6% 4 3 4 3 5% 7% 47%	2280
	11th to 20th	Day	11% 5% 2 5% 3 3 4 3 5% 7% 51%	2271
	21st to end	Day	13% 6% 2 6% 5% 4 4 3 5% 7% 45%	2047
October	1st to 10th	Day	13% 7% 2 6% 4 3 3 3 5% 6% 48%	1900
	11th to 20th	Day	17% 9% 3 7% 4 4 4 3 4 7% 39%	1900
	21st to end	Day	17% 9% 3 6% 4 4 3 2 5% 6% 41%	1990
November	1st to 10th	Day	11% 9% 3 8% 4 4 4 3 5% 5% 44%	1762
	11th to 20th	Day	13% 12% 5% 9% 5% 4 4 4 5% 6% 33%	1730
	21st to end	Day	14% 12% 4 9% 5% 3 3 3 5% 6% 37%	1600
December	1st to 10th	Day	13% 12% 4 11% 6% 4 4 3 4 5% 33%	1584
	11th to 20th	Day	13% 13% 5% 10% 5% 4 5% 4 5% 7% 29%	1918
	21st to end	Day	19% 22% 10% 11% 4 4 2 2 4 4 16%	2783
January	1st to 10th	Night	10% 13% 7% 14% 6% 5% 4 3 4 5% 29%	4428
	11th to 20th	Night	12% 16% 6% 13% 6% 5% 4 5% 7% 4 21%	4440
	21st to end	Night	16% 19% 8% 10% 6% 4 4 3 3 5% 23%	4588
February	1st to 10th	Night	11% 13% 4 9% 7% 5% 4 3 4 4 33%	2470
	11th to 20th	Night	10% 10% 3 8% 6% 4 4 3 4 6% 41%	2335
	21st to end	Night	15% 12% 3 7% 4 4 4 3 4 6% 37%	1884
March	1st to 10th	Night	18% 11% 3 6% 4 3 4 3 3 4 43%	3733
	11th to 20th	Night	9% 6% 3 6% 4 4 4 3 5% 7% 49%	3485
	21st to end	Night	24% 13% 5% 11% 4 4 4 3 4 4 24%	3604
April	1st to 10th	Night	15% 10% 3 7% 5% 3 4 3 5% 6% 40%	1900
	11th to 20th	Night	16% 10% 2 7% 3 4 5% 3 4 6% 40%	1875
	21st to end	Night	16% 9% 3 7% 5% 4 4 4 5% 6% 37%	1900
May	1st to 10th	Night	18% 7% 3 7% 5% 5% 4 3 6% 7% 36%	2601
	11th to 20th	Night	12% 7% 2 8% 5% 5% 5% 3 4 6% 42%	2506
	21st to end	Night	10% 5% 2 5% 3 4 4 4 7% 8% 47%	2743
June	1st to 10th	Night	8% 5% 2 6% 5% 4 4 4 7% 8% 47%	1520
	11th to 20th	Night	9% 5% 2 6% 4 4 5% 4 7% 10% 45%	1520
	21st to end	Night	10% 5% 2 6% 4 4 4 4 7% 7% 45%	1520
July	1st to 10th	Night	12% 7% 3 6% 5% 4 5% 3 6% 9% 40%	2530
	11th to 20th	Night	4 3 2 4 4 3 4 3 7% 10% 57%	2530
	21st to end	Night	5% 4 2 6% 4 5% 5% 5% 7% 9% 48%	2750
August	1st to 10th	Night	7% 5% 2 5% 4 4 5% 4 6% 9% 51%	2767
	11th to 20th	Night	9% 5% 2 5% 4 4 4 3 5% 8% 51%	2938
	21st to end	Night	9% 5% 2 6% 4 4 3 3 5% 8% 51%	3476
September	1st to 10th	Night	10% 4 2 5% 2 3 4 3 5% 6% 56%	1900
	11th to 20th	Night	11% 5% 2 5% 4 4 4 3 4 8% 51%	1900
	21st to end	Night	9% 5% 1 5% 3 4 4 4 6% 6% 52%	2120
October	1st to 10th	Night	11% 5% 1 5% 4 4 3 4 4 6% 52%	2280
	11th to 20th	Night	15% 7% 3 5% 4 3 3 3 5% 7% 44%	2280
	21st to end	Night	17% 8% 3 7% 5% 4 4 3 4 6% 39%	2608
November	1st to 10th	Night	11% 7% 3 7% 4 3 3 3 5% 6% 49%	2536
	11th to 20th	Night	14% 10% 4 8% 5% 4 4 3 5% 6% 36%	2665
	21st to end	Night	16% 10% 4 8% 5% 3 4 3 4 5% 38%	2800
December	1st to 10th	Night	13% 11% 4 11% 6% 5% 5% 3 5% 6% 31%	2779
	11th to 20th	Night	13% 13% 5% 10% 5% 4 5% 4 5% 6% 31%	3279
	21st to end	Night	19% 17% 6% 13% 6% 5% 5% 4 4 4 18%	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	62% 5% 12% 15% 6%	2528
	11th to 20th	Day	57% 9% 15% 12% 7% 1	2530
	21st to end	Day	65% 5% 12% 13% 5%	3075
February	1st to 10th	Day	52% 6% 13% 18% 9% 1	1710
	11th to 20th	Day	46% 5% 13% 24% 10% 2	1739
	21st to end	Day	50% 7% 11% 19% 10% 2	1570
March	1st to 10th	Day	41% 7% 11% 26% 13% 3	3142
	11th to 20th	Day	39% 7% 12% 31% 11% 1	3480
	21st to end	Day	61% 9% 12% 14% 4 1	4025
April	1st to 10th	Day	51% 7% 10% 22% 10%	2280
	11th to 20th	Day	50% 7% 9% 21% 12% 2	2254
	21st to end	Day	50% 6% 9% 20% 12% 2	2280
May	1st to 10th	Day	46% 8% 11% 20% 15%	4337
	11th to 20th	Day	41% 8% 10% 28% 12%	4403
	21st to end	Day	41% 9% 10% 22% 15% 3	4837
June	1st to 10th	Day	35% 8% 14% 24% 17% 1	2660
	11th to 20th	Day	38% 7% 13% 22% 18% 2	2660
	21st to end	Day	40% 8% 14% 23% 12% 2	2660
July	1st to 10th	Day	43% 8% 14% 25% 8% 1	4371
	11th to 20th	Day	26% 8% 16% 31% 17% 1	4365
	21st to end	Day	37% 10% 15% 18% 18% 2	4662
August	1st to 10th	Day	38% 8% 15% 26% 12% 1	4153
	11th to 20th	Day	35% 7% 13% 30% 14% 1	3935
	21st to end	Day	33% 6% 15% 31% 15% 2	4179
September	1st to 10th	Day	38% 5% 12% 25% 19% 2	2280
	11th to 20th	Day	32% 7% 11% 31% 17% 2	2271
	21st to end	Day	38% 6% 11% 28% 16% 2	2047
October	1st to 10th	Day	23% 5% 7% 38% 26% 1	3160
	11th to 20th	Day	33% 4 10% 25% 24% 3	3140
	21st to end	Day	41% 4 11% 28% 13% 2	3254
November	1st to 10th	Day	42% 5% 13% 25% 13% 2	1762
	11th to 20th	Day	52% 5% 13% 20% 10% 1	1730
	21st to end	Day	49% 5% 16% 22% 7% 1	1600
December	1st to 10th	Day	54% 5% 13% 18% 8% 2	1584
	11th to 20th	Day	54% 6% 17% 14% 9% 1	1915
	21st to end	Day	72% 6% 10% 8% 4	2783
January	1st to 10th	Night	57% 6% 12% 18% 8%	4428
	11th to 20th	Night	61% 6% 12% 13% 7%	4440
	21st to end	Night	65% 5% 9% 15% 5% 1	4588
February	1st to 10th	Night	53% 6% 11% 18% 11% 1	2470
	11th to 20th	Night	46% 5% 12% 23% 13% 1	2336
	21st to end	Night	49% 5% 12% 20% 11% 3	1884
March	1st to 10th	Night	46% 5% 10% 23% 13% 3	3733
	11th to 20th	Night	34% 6% 11% 32% 16% 2	3485
	21st to end	Night	63% 5% 8% 17% 6% 1	3604
April	1st to 10th	Night	46% 5% 11% 23% 13% 1	1900
	11th to 20th	Night	45% 5% 10% 19% 17% 4	1875
	21st to end	Night	46% 6% 13% 19% 13% 2	1900
May	1st to 10th	Night	45% 8% 11% 17% 17% 2	2626
	11th to 20th	Night	40% 8% 11% 24% 16% 1	2507
	21st to end	Night	32% 8% 14% 26% 19% 2	2751
June	1st to 10th	Night	31% 9% 15% 25% 18% 2	1520
	11th to 20th	Night	34% 6% 12% 24% 21% 3	1520
	21st to end	Night	35% 9% 13% 23% 16% 4	1520
July	1st to 10th	Night	40% 7% 15% 23% 12% 3	2490
	11th to 20th	Night	22% 7% 16% 35% 18% 2	2482
	21st to end	Night	31% 10% 17% 20% 20% 3	2662
August	1st to 10th	Night	30% 7% 15% 30% 18% 1	2758
	11th to 20th	Night	30% 6% 15% 32% 16% 1	2965
	21st to end	Night	31% 7% 12% 28% 18% 4	3476
September	1st to 10th	Night	28% 7% 12% 27% 26% 2	1900
	11th to 20th	Night	32% 5% 12% 31% 17% 3	1900
	21st to end	Night	31% 6% 10% 30% 21% 2	2120
October	1st to 10th	Night	23% 5% 7% 34% 30% 2	3800
	11th to 20th	Night	29% 5% 10% 22% 31% 3	3779
	21st to end	Night	45% 5% 9% 25% 15% 2	4294
November	1st to 10th	Night	38% 5% 12% 25% 18% 3	2536
	11th to 20th	Night	51% 5% 13% 20% 11% 1	2665
	21st to end	Night	48% 5% 13% 24% 9% 1	2800
December	1st to 10th	Night	54% 5% 12% 20% 8% 1	2779
	11th to 20th	Night	53% 6% 14% 19% 7% 1	3281
	21st to end	Night	68% 7% 8% 12% 4	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	18% 17% 29% 25% 10% 1	270
	11th to 20th	Day	23% 14% 42% 16% 4 1	270
	21st to end	Day	22% 17% 38% 18% 4 1	297
February	1st to 10th	Day	17% 24% 37% 17% 4	270
	11th to 20th	Day	20% 27% 28% 20% 4 1	270
	21st to end	Day	23% 20% 45% 9% 3	225
March	1st to 10th	Day	16% 24% 40% 17% 3	270
	11th to 20th	Day	17% 24% 37% 17% 4 2	270
	21st to end	Day	30% 14% 33% 17% 5% 1	418
April	1st to 10th	Day	25% 17% 34% 19% 4	460
	11th to 20th	Day	26% 20% 25% 19% 9% 1	452
	21st to end	Day	24% 17% 29% 19% 10% 1	460
May	1st to 10th	Day	20% 13% 34% 23% 9% 1	610
	11th to 20th	Day	21% 13% 28% 24% 11% 3	675
	21st to end	Day	16% 13% 26% 27% 13% 5%	734
June	1st to 10th	Day	11% 8% 27% 33% 17% 5%	680
	11th to 20th	Day	15% 7% 31% 31% 12% 4	680
	21st to end	Day	14% 8% 31% 30% 12% 5%	680
July	1st to 10th	Day	8% 5% 20% 32% 23% 11%	671
	11th to 20th	Day	7% 6% 28% 32% 21% 7%	668
	21st to end	Day	8% 4 27% 34% 21% 6%	739
August	1st to 10th	Day	6% 3 24% 34% 24% 8%	676
	11th to 20th	Day	14% 5% 21% 28% 20% 12%	585
	21st to end	Day	10% 6% 22% 32% 22% 8%	539
September	1st to 10th	Day	14% 8% 23% 29% 20% 5%	490
	11th to 20th	Day	11% 5% 21% 32% 23% 7%	490
	21st to end	Day	14% 13% 27% 26% 16% 4	447
October	1st to 10th	Day	17% 10% 32% 26% 13% 3	300
	11th to 20th	Day	24% 18% 33% 18% 7%	300
	21st to end	Day	26% 16% 31% 20% 6% 1	330
November	1st to 10th	Day	16% 16% 37% 20% 8% 2	300
	11th to 20th	Day	20% 22% 34% 18% 6% 1	300
	21st to end	Day	24% 14% 39% 19% 4	300
December	1st to 10th	Day	17% 17% 40% 18% 6% 1	294
	11th to 20th	Day	18% 16% 38% 20% 7% 1	270
	21st to end	Day	27% 19% 38% 14% 3	297
January	1st to 10th	Night	15% 17% 36% 26% 7%	950
	11th to 20th	Night	19% 14% 37% 24% 5%	950
	21st to end	Night	21% 13% 35% 26% 5%	1045
February	1st to 10th	Night	18% 14% 39% 24% 5%	950
	11th to 20th	Night	17% 15% 39% 25% 4	861
	21st to end	Night	23% 14% 39% 20% 3	628
March	1st to 10th	Night	23% 13% 36% 22% 5%	760
	11th to 20th	Night	17% 12% 35% 29% 6%	575
	21st to end	Night	24% 12% 34% 24% 5% 1	627
April	1st to 10th	Night	20% 14% 38% 24% 4	570
	11th to 20th	Night	22% 14% 29% 27% 7% 1	563
	21st to end	Night	21% 10% 33% 26% 8% 1	570
May	1st to 10th	Night	18% 10% 36% 29% 6% 1	570
	11th to 20th	Night	18% 7% 33% 31% 11%	561
	21st to end	Night	13% 6% 30% 34% 15% 1	617
June	1st to 10th	Night	10% 5% 27% 45% 13% 1	570
	11th to 20th	Night	13% 4 29% 41% 12% 1	570
	21st to end	Night	13% 3 28% 41% 14% 1	570
July	1st to 10th	Night	9% 2 15% 41% 29% 4	555
	11th to 20th	Night	7% 3 23% 40% 25% 3	552
	21st to end	Night	7% 2 19% 46% 25% 2	624
August	1st to 10th	Night	7% 2 17% 45% 28% 2	567
	11th to 20th	Night	8% 3 15% 41% 29% 4	564
	21st to end	Night	11% 2 17% 45% 22% 3	627
September	1st to 10th	Night	12% 4 20% 38% 22% 4	570
	11th to 20th	Night	12% 3 21% 35% 26% 4	570
	21st to end	Night	11% 8% 27% 35% 17% 1	750
October	1st to 10th	Night	15% 7% 28% 31% 18% 2	760
	11th to 20th	Night	20% 12% 33% 27% 9%	760
	21st to end	Night	22% 11% 33% 26% 6%	836
November	1st to 10th	Night	17% 11% 38% 24% 9%	780
	11th to 20th	Night	19% 17% 36% 22% 5%	865
	21st to end	Night	21% 14% 36% 22% 7%	1000
December	1st to 10th	Night	20% 14% 38% 23% 5% 1	993
	11th to 20th	Night	23% 12% 35% 25% 5%	950
	21st to end	Night	26% 15% 36% 20% 3	1045

Page generated at 2024-12-06 02:54:53. Version ac07

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