Hannibal
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hannibal 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	11% 8% 3 7% 5% 4 4 4 6% 8% 40%	138313
	Night	12% 8% 3 7% 4 4 4 3 5% 7% 42%	134681
Transparency	Day	29% 34% 8% 17% 11% 1	141908
	Night	29% 34% 7% 16% 12% 2	139165
Seeing	Day	14% 10% 28% 27% 16% 5%	18032
	Night	16% 9% 31% 30% 13% 1	27839

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	12% 11% 5% 12% 6% 5% 4 3 5% 6% 30%	4691
	11th to 20th	Day	7% 8% 3 9% 7% 6% 6% 4 6% 6% 38%	5147
	21st to end	Day	14% 15% 7% 9% 5% 4 3 3 3 4 33%	5812
February	1st to 10th	Day	15% 10% 4 9% 5% 5% 5% 3 5% 7% 32%	1890
	11th to 20th	Day	13% 11% 3 8% 5% 5% 6% 4 5% 6% 35%	1942
	21st to end	Day	13% 10% 4 7% 5% 4 4 3 4 6% 40%	1730
March	1st to 10th	Day	17% 10% 3 5% 3 3 3 2 4 4 47%	4802
	11th to 20th	Day	8% 6% 2 5% 4 3 5% 3 5% 8% 50%	5090
	21st to end	Day	15% 10% 4 8% 5% 5% 5% 3 5% 7% 33%	5788
April	1st to 10th	Day	14% 8% 3 8% 4 4 4 4 5% 6% 38%	2520
	11th to 20th	Day	15% 7% 2 8% 5% 4 3 3 5% 7% 40%	2494
	21st to end	Day	18% 6% 3 7% 4 4 4 4 6% 8% 35%	2520
May	1st to 10th	Day	13% 8% 3 7% 5% 5% 5% 4 7% 9% 36%	7410
	11th to 20th	Day	13% 7% 3 7% 4 4 4 3 6% 8% 42%	8222
	21st to end	Day	14% 8% 3 8% 5% 5% 5% 4 6% 7% 35%	9047
June	1st to 10th	Day	6% 4 2 6% 4 6% 5% 5% 7% 9% 46%	2940
	11th to 20th	Day	7% 5% 2 6% 4 4 5% 4 8% 9% 46%	2940
	21st to end	Day	8% 5% 2 6% 5% 5% 5% 4 6% 9% 44%	2940
July	1st to 10th	Day	9% 6% 2 7% 4 4 5% 4 7% 10% 42%	6500
	11th to 20th	Day	7% 6% 3 7% 5% 5% 5% 5% 7% 10% 39%	6431
	21st to end	Day	8% 6% 2 7% 5% 5% 6% 5% 8% 11% 36%	6522
August	1st to 10th	Day	4 4 2 5% 4 4 5% 5% 8% 11% 48%	4234
	11th to 20th	Day	12% 6% 2 6% 4 4 5% 4 6% 10% 42%	3974
	21st to end	Day	5% 4 2 5% 3 4 5% 4 7% 10% 51%	4312
September	1st to 10th	Day	10% 6% 2 4 3 4 4 3 5% 7% 52%	2400
	11th to 20th	Day	9% 4 2 5% 4 4 3 4 6% 8% 51%	2400
	21st to end	Day	8% 5% 1 5% 4 5% 4 4 6% 8% 51%	2130
October	1st to 10th	Day	11% 6% 2 5% 3 3 4 4 4 6% 53%	2000
	11th to 20th	Day	14% 7% 3 6% 3 3 3 3 4 5% 48%	2000
	21st to end	Day	17% 8% 3 6% 4 3 3 3 4 6% 44%	2200
November	1st to 10th	Day	11% 7% 3 5% 3 3 3 3 5% 6% 52%	1862
	11th to 20th	Day	14% 7% 3 7% 4 3 3 2 5% 6% 44%	1890
	21st to end	Day	17% 11% 3 7% 4 4 3 4 4 5% 38%	1685
December	1st to 10th	Day	7% 9% 3 6% 5% 3 3 3 4 6% 51%	2690
	11th to 20th	Day	13% 9% 6% 10% 4 5% 4 3 5% 7% 34%	3088
	21st to end	Day	20% 20% 6% 11% 5% 4 4 3 3 5% 19%	4070
January	1st to 10th	Night	12% 12% 6% 12% 5% 4 4 3 4 5% 33%	8232
	11th to 20th	Night	10% 10% 4 10% 5% 5% 6% 4 5% 5% 36%	7828
	21st to end	Night	14% 14% 5% 10% 5% 4 3 3 4 6% 33%	8402
February	1st to 10th	Night	14% 12% 5% 7% 5% 5% 4 4 5% 6% 34%	2730
	11th to 20th	Night	14% 9% 3 7% 5% 5% 4 4 4 7% 38%	2564
	21st to end	Night	15% 8% 3 7% 4 4 3 3 4 6% 42%	2076
March	1st to 10th	Night	18% 11% 4 6% 3 3 3 2 4 4 42%	5316
	11th to 20th	Night	11% 7% 2 5% 4 3 3 3 4 6% 51%	5090
	21st to end	Night	16% 9% 3 7% 6% 4 5% 4 5% 7% 32%	5383
April	1st to 10th	Night	13% 7% 3 7% 5% 4 3 3 5% 6% 44%	2100
	11th to 20th	Night	14% 7% 2 6% 4 5% 3 4 5% 6% 44%	2075
	21st to end	Night	16% 8% 3 7% 4 3 4 3 4 6% 41%	2100
May	1st to 10th	Night	15% 8% 3 7% 5% 5% 5% 4 5% 7% 37%	5441
	11th to 20th	Night	10% 6% 2 6% 4 5% 4 4 5% 8% 45%	4670
	21st to end	Night	13% 7% 3 7% 5% 4 4 4 6% 8% 39%	5139
June	1st to 10th	Night	7% 5% 2 4 3 4 4 4 6% 9% 52%	1680
	11th to 20th	Night	7% 5% 2 6% 4 4 4 4 6% 9% 49%	1680
	21st to end	Night	6% 4 2 5% 4 5% 5% 5% 6% 9% 50%	1680
July	1st to 10th	Night	8% 6% 2 7% 4 4 4 4 6% 9% 45%	3698
	11th to 20th	Night	5% 4 2 7% 5% 4 5% 4 7% 9% 47%	3657
	21st to end	Night	8% 5% 2 7% 5% 4 5% 5% 7% 11% 41%	4345
August	1st to 10th	Night	3 3 1 4 3 3 4 4 6% 10% 58%	2926
	11th to 20th	Night	9% 5% 2 5% 4 4 4 3 5% 7% 52%	3076
	21st to end	Night	4 3 1 5% 3 4 5% 4 7% 11% 54%	3586
September	1st to 10th	Night	10% 5% 1 4 3 4 4 4 5% 6% 56%	2000
	11th to 20th	Night	7% 6% 2 6% 4 4 4 4 6% 7% 52%	2000
	21st to end	Night	7% 4 2 5% 4 4 4 3 4 7% 55%	2245
October	1st to 10th	Night	8% 4 2 4 3 3 3 4 5% 7% 57%	2400
	11th to 20th	Night	14% 5% 1 5% 3 3 4 3 4 5% 52%	2400
	21st to end	Night	17% 8% 2 5% 4 3 3 3 5% 5% 44%	2640
November	1st to 10th	Night	10% 7% 2 6% 3 3 3 3 4 6% 53%	2653
	11th to 20th	Night	12% 8% 3 6% 5% 4 3 3 5% 6% 47%	2730
	21st to end	Night	17% 10% 3 6% 3 3 3 3 5% 6% 40%	2930
December	1st to 10th	Night	10% 8% 3 7% 5% 3 4 4 5% 6% 46%	4720
	11th to 20th	Night	14% 9% 3 7% 4 4 4 4 5% 6% 40%	5339
	21st to end	Night	23% 17% 6% 10% 5% 4 4 3 4 4 21%	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	47% 20% 8% 17% 7% 1	4692
	11th to 20th	Day	36% 20% 10% 16% 13% 4	5147
	21st to end	Day	45% 21% 6% 17% 9% 2	5812
February	1st to 10th	Day	21% 59% 6% 9% 5% 1	1890
	11th to 20th	Day	23% 58% 3 9% 6% 1	1951
	21st to end	Day	19% 58% 3 11% 8% 1	1730
March	1st to 10th	Day	31% 27% 4 18% 19% 1	4802
	11th to 20th	Day	21% 27% 5% 24% 19% 3	5090
	21st to end	Day	36% 27% 12% 19% 5%	5790
April	1st to 10th	Day	24% 58% 4 8% 5%	2520
	11th to 20th	Day	19% 59% 4 11% 7%	2494
	21st to end	Day	20% 59% 5% 9% 6% 1	2520
May	1st to 10th	Day	36% 21% 10% 20% 12%	7445
	11th to 20th	Day	33% 21% 9% 22% 12% 2	8226
	21st to end	Day	39% 22% 7% 19% 14%	9061
June	1st to 10th	Day	14% 59% 6% 12% 7% 2	2940
	11th to 20th	Day	16% 60% 4 11% 7% 1	2940
	21st to end	Day	17% 58% 8% 11% 5% 1	2940
July	1st to 10th	Day	30% 25% 9% 22% 13% 1	6431
	11th to 20th	Day	33% 26% 11% 21% 10%	6356
	21st to end	Day	31% 26% 16% 21% 6%	6337
August	1st to 10th	Day	19% 36% 11% 28% 7%	4220
	11th to 20th	Day	27% 36% 8% 19% 10%	4013
	21st to end	Day	20% 36% 13% 22% 7% 2	4311
September	1st to 10th	Day	12% 57% 6% 13% 9% 2	2400
	11th to 20th	Day	12% 56% 6% 14% 9% 3	2400
	21st to end	Day	15% 57% 4 12% 11% 1	2130
October	1st to 10th	Day	13% 35% 2 7% 38% 4	3260
	11th to 20th	Day	12% 35% 3 14% 29% 7%	3240
	21st to end	Day	27% 35% 4 15% 19% 1	3538
November	1st to 10th	Day	17% 53% 6% 13% 10% 2	1862
	11th to 20th	Day	19% 54% 3 12% 11% 2	1890
	21st to end	Day	26% 54% 4 12% 5%	1685
December	1st to 10th	Day	21% 33% 12% 23% 11%	2690
	11th to 20th	Day	36% 30% 8% 16% 9% 1	3085
	21st to end	Day	58% 25% 8% 7% 3	4070
January	1st to 10th	Night	46% 20% 12% 17% 5%	8233
	11th to 20th	Night	41% 20% 6% 17% 14% 2	7828
	21st to end	Night	44% 21% 8% 17% 9% 1	8402
February	1st to 10th	Night	21% 58% 5% 10% 5% 1	2730
	11th to 20th	Night	21% 57% 5% 10% 7%	2565
	21st to end	Night	17% 59% 4 9% 10% 2	2076
March	1st to 10th	Night	37% 27% 3 15% 17% 1	5316
	11th to 20th	Night	24% 27% 3 22% 19% 5%	5090
	21st to end	Night	37% 27% 7% 21% 6% 2	5383
April	1st to 10th	Night	21% 59% 5% 9% 5% 1	2100
	11th to 20th	Night	16% 60% 6% 10% 7% 1	2075
	21st to end	Night	20% 59% 4 9% 8% 1	2100
May	1st to 10th	Night	39% 22% 8% 21% 9% 1	5471
	11th to 20th	Night	30% 21% 11% 21% 12% 4	4671
	21st to end	Night	37% 21% 8% 15% 17% 1	5149
June	1st to 10th	Night	11% 59% 7% 12% 8% 2	1680
	11th to 20th	Night	15% 59% 4 11% 9% 1	1680
	21st to end	Night	12% 59% 8% 14% 6% 1	1680
July	1st to 10th	Night	29% 25% 9% 23% 13% 1	3660
	11th to 20th	Night	27% 25% 11% 23% 13%	3612
	21st to end	Night	29% 26% 16% 21% 8%	4219
August	1st to 10th	Night	14% 36% 13% 25% 11%	2916
	11th to 20th	Night	23% 36% 8% 19% 14%	3103
	21st to end	Night	18% 36% 15% 22% 8% 1	3586
September	1st to 10th	Night	11% 57% 5% 12% 12% 3	2000
	11th to 20th	Night	13% 57% 4 13% 11% 2	2000
	21st to end	Night	16% 56% 4 11% 12% 1	2245
October	1st to 10th	Night	12% 35% 3 12% 35% 3	3920
	11th to 20th	Night	13% 35% 5% 13% 29% 4	3899
	21st to end	Night	23% 35% 4 16% 19% 3	4252
November	1st to 10th	Night	18% 53% 4 13% 9% 3	2653
	11th to 20th	Night	18% 54% 3 12% 12% 2	2730
	21st to end	Night	24% 54% 4 12% 7%	2930
December	1st to 10th	Night	25% 34% 6% 25% 10% 1	4720
	11th to 20th	Night	31% 31% 8% 18% 11% 1	5341
	21st to end	Night	56% 25% 8% 8% 3 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	17% 18% 35% 24% 5%	330
	11th to 20th	Day	23% 20% 42% 13% 2	330
	21st to end	Day	17% 20% 41% 19% 3	363
February	1st to 10th	Day	23% 15% 42% 17% 4	330
	11th to 20th	Day	22% 18% 37% 17% 5%	330
	21st to end	Day	21% 18% 42% 16% 3	273
March	1st to 10th	Day	19% 20% 43% 17% 1	330
	11th to 20th	Day	22% 18% 34% 21% 4 1	330
	21st to end	Day	28% 18% 35% 15% 3	452
April	1st to 10th	Day	22% 16% 34% 19% 6% 1	540
	11th to 20th	Day	19% 18% 32% 22% 8% 1	532
	21st to end	Day	20% 12% 37% 23% 7% 1	540
May	1st to 10th	Day	16% 12% 37% 22% 10% 2	643
	11th to 20th	Day	19% 11% 26% 27% 13% 3	775
	21st to end	Day	14% 8% 28% 28% 16% 6%	844
June	1st to 10th	Day	8% 5% 23% 33% 23% 8%	780
	11th to 20th	Day	9% 5% 25% 35% 22% 5%	780
	21st to end	Day	9% 7% 29% 34% 18% 3	780
July	1st to 10th	Day	9% 3 14% 34% 26% 13%	771
	11th to 20th	Day	8% 4 19% 37% 26% 7%	744
	21st to end	Day	10% 2 17% 32% 32% 7%	794
August	1st to 10th	Day	7% 2 16% 41% 26% 8%	726
	11th to 20th	Day	8% 2 17% 32% 31% 10%	596
	21st to end	Day	8% 2 14% 32% 31% 12%	583
September	1st to 10th	Day	12% 5% 16% 30% 28% 9%	530
	11th to 20th	Day	7% 3 15% 33% 29% 14%	530
	21st to end	Day	10% 7% 22% 30% 20% 11%	440
October	1st to 10th	Day	15% 7% 28% 28% 15% 8%	330
	11th to 20th	Day	13% 21% 30% 24% 11% 1	330
	21st to end	Day	24% 18% 33% 21% 4 1	363
November	1st to 10th	Day	12% 12% 39% 24% 9% 4	330
	11th to 20th	Day	19% 17% 32% 24% 7% 2	330
	21st to end	Day	24% 15% 31% 23% 6% 1	330
December	1st to 10th	Day	13% 13% 45% 20% 5% 3	330
	11th to 20th	Day	18% 18% 36% 22% 5%	330
	21st to end	Day	26% 21% 35% 14% 4	363
January	1st to 10th	Night	16% 15% 40% 23% 6%	1050
	11th to 20th	Night	19% 17% 37% 22% 4	1050
	21st to end	Night	19% 14% 40% 25% 2	1155
February	1st to 10th	Night	20% 12% 39% 25% 4	1050
	11th to 20th	Night	19% 16% 35% 25% 3	930
	21st to end	Night	19% 17% 39% 23% 2	692
March	1st to 10th	Night	20% 15% 41% 20% 4	767
	11th to 20th	Night	20% 12% 35% 28% 5%	630
	21st to end	Night	24% 13% 35% 24% 4	693
April	1st to 10th	Night	16% 16% 37% 27% 4	630
	11th to 20th	Night	18% 12% 35% 27% 8%	623
	21st to end	Night	20% 8% 36% 31% 6%	630
May	1st to 10th	Night	15% 8% 35% 34% 8%	630
	11th to 20th	Night	16% 6% 29% 35% 13% 1	621
	21st to end	Night	12% 4 27% 35% 20% 2	683
June	1st to 10th	Night	9% 3 21% 42% 24% 1	630
	11th to 20th	Night	10% 2 21% 43% 21% 1	630
	21st to end	Night	6% 2 27% 43% 20% 1	630
July	1st to 10th	Night	10% 3 10% 38% 36% 4	615
	11th to 20th	Night	8% 1 16% 43% 29% 3	597
	21st to end	Night	9% 1 12% 42% 35% 1	657
August	1st to 10th	Night	6% 2 11% 49% 29% 3	597
	11th to 20th	Night	8% 2 12% 41% 33% 5%	594
	21st to end	Night	7% 1 11% 39% 40% 3	660
September	1st to 10th	Night	12% 2 17% 38% 27% 5%	600
	11th to 20th	Night	8% 3 20% 35% 29% 5%	600
	21st to end	Night	9% 5% 23% 34% 23% 4	760
October	1st to 10th	Night	10% 4 27% 34% 22% 3	800
	11th to 20th	Night	17% 9% 32% 30% 11% 1	800
	21st to end	Night	22% 11% 33% 27% 6%	880
November	1st to 10th	Night	15% 10% 36% 30% 9%	820
	11th to 20th	Night	16% 14% 38% 27% 5%	840
	21st to end	Night	23% 11% 35% 24% 6%	1040
December	1st to 10th	Night	18% 12% 38% 27% 5% 1	1050
	11th to 20th	Night	23% 11% 34% 26% 6%	1050
	21st to end	Night	25% 16% 34% 23% 3	1155

Page generated at 2026-07-13 02:14:50. Version ac07

Copyright © 2026 Attilla Danko.