Dave's Falls County Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Dave's Falls County Park clear sky chart from 2005-11-06 to 2024-11-05.

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	13% 9% 3 8% 5% 5% 5% 4 6% 7% 36%	101530
	Night	14% 10% 4 8% 5% 4 4 3 5% 6% 37%	97609
Transparency	Day	45% 7% 13% 22% 12% 1	105037
	Night	46% 7% 13% 23% 11% 1	102243
Seeing	Day	18% 15% 32% 22% 10% 3	16030
	Night	18% 10% 33% 28% 9% 1	25897

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	13% 13% 5% 10% 6% 6% 6% 4 6% 6% 26%	2527
	11th to 20th	Day	13% 12% 5% 11% 6% 5% 5% 4 7% 7% 24%	2530
	21st to end	Day	13% 18% 6% 13% 6% 5% 4 3 5% 6% 22%	2783
February	1st to 10th	Day	9% 12% 3 9% 6% 5% 4 3 6% 7% 35%	1633
	11th to 20th	Day	10% 12% 3 10% 6% 4 5% 4 5% 6% 35%	1796
	21st to end	Day	12% 13% 5% 8% 5% 3 4 4 5% 7% 34%	1570
March	1st to 10th	Day	11% 11% 3 6% 5% 3 4 3 5% 6% 44%	3120
	11th to 20th	Day	8% 11% 3 10% 7% 6% 5% 3 5% 7% 34%	3266
	21st to end	Day	20% 12% 4 11% 6% 5% 4 3 4 4 26%	4165
April	1st to 10th	Day	16% 14% 4 8% 6% 5% 4 5% 5% 6% 29%	2280
	11th to 20th	Day	20% 11% 3 7% 5% 4 5% 3 5% 6% 32%	2254
	21st to end	Day	18% 9% 3 7% 4 5% 6% 3 5% 6% 34%	2465
May	1st to 10th	Day	15% 7% 3 8% 5% 5% 5% 4 5% 6% 39%	4232
	11th to 20th	Day	13% 6% 3 7% 5% 5% 4 4 6% 7% 41%	4399
	21st to end	Day	13% 7% 3 7% 5% 5% 5% 4 6% 8% 37%	4824
June	1st to 10th	Day	12% 6% 2 6% 5% 5% 4 4 6% 8% 42%	2660
	11th to 20th	Day	14% 6% 2 7% 6% 5% 5% 4 6% 7% 38%	2660
	21st to end	Day	13% 7% 2 6% 5% 4 5% 4 6% 8% 38%	2660
July	1st to 10th	Day	15% 5% 1 6% 5% 5% 6% 4 6% 9% 38%	4440
	11th to 20th	Day	5% 4 2 4 4 6% 6% 4 7% 9% 49%	4440
	21st to end	Day	8% 5% 2 6% 4 4 5% 4 6% 8% 47%	4813
August	1st to 10th	Day	9% 5% 3 8% 5% 5% 6% 4 7% 9% 39%	4423
	11th to 20th	Day	12% 5% 2 6% 4 4 4 4 5% 7% 48%	4031
	21st to end	Day	14% 6% 2 7% 4 5% 5% 4 5% 7% 41%	4180
September	1st to 10th	Day	12% 6% 2 7% 5% 4 4 4 6% 7% 43%	2280
	11th to 20th	Day	11% 5% 2 6% 4 6% 5% 5% 7% 9% 42%	2171
	21st to end	Day	12% 6% 2 8% 5% 5% 6% 5% 7% 8% 36%	2090
October	1st to 10th	Day	16% 6% 2 7% 4 4 5% 4 6% 7% 39%	2005
	11th to 20th	Day	20% 11% 3 8% 5% 6% 4 3 6% 8% 27%	1826
	21st to end	Day	21% 10% 3 8% 5% 5% 5% 4 4 6% 30%	1881
November	1st to 10th	Day	13% 10% 3 8% 4 4 5% 4 4 7% 38%	1708
	11th to 20th	Day	15% 11% 5% 8% 6% 5% 6% 4 6% 7% 27%	1677
	21st to end	Day	15% 13% 4 8% 5% 4 5% 4 7% 8% 29%	1520
December	1st to 10th	Day	11% 13% 4 9% 6% 5% 5% 4 6% 6% 32%	1520
	11th to 20th	Day	16% 14% 4 9% 5% 6% 5% 5% 5% 6% 26%	1918
	21st to end	Day	22% 22% 6% 10% 5% 4 3 2 4 4 19%	2783
January	1st to 10th	Night	13% 14% 6% 11% 5% 4 4 3 4 4 32%	4428
	11th to 20th	Night	11% 15% 6% 11% 7% 6% 5% 4 5% 6% 24%	4440
	21st to end	Night	12% 17% 8% 11% 6% 4 4 3 4 6% 24%	4884
February	1st to 10th	Night	9% 13% 5% 10% 6% 6% 4 3 5% 6% 33%	2546
	11th to 20th	Night	10% 11% 4 9% 6% 4 5% 4 6% 7% 35%	2269
	21st to end	Night	14% 14% 5% 8% 5% 4 3 3 5% 5% 34%	1884
March	1st to 10th	Night	12% 9% 3 6% 4 4 4 3 5% 7% 44%	3733
	11th to 20th	Night	9% 10% 4 9% 5% 5% 5% 4 6% 7% 37%	3724
	21st to end	Night	17% 10% 4 10% 6% 5% 5% 3 5% 6% 28%	3466
April	1st to 10th	Night	19% 10% 3 9% 5% 4 5% 3 5% 7% 30%	1900
	11th to 20th	Night	21% 7% 3 6% 4 3 4 4 5% 6% 37%	1875
	21st to end	Night	16% 8% 3 8% 5% 5% 4 3 5% 7% 36%	1713
May	1st to 10th	Night	17% 7% 3 7% 4 4 4 4 5% 7% 38%	2663
	11th to 20th	Night	12% 9% 3 7% 5% 4 4 4 5% 6% 43%	2506
	21st to end	Night	18% 6% 2 6% 5% 4 5% 4 5% 7% 39%	2743
June	1st to 10th	Night	11% 5% 2 5% 5% 4 4 4 5% 8% 46%	1520
	11th to 20th	Night	13% 7% 3 7% 4 4 5% 4 7% 7% 39%	1520
	21st to end	Night	13% 6% 2 5% 4 3 4 4 7% 9% 43%	1520
July	1st to 10th	Night	14% 5% 2 6% 3 4 5% 4 6% 7% 44%	2530
	11th to 20th	Night	6% 3 1 4 3 3 4 4 5% 9% 56%	2530
	21st to end	Night	9% 6% 2 6% 4 3 3 3 5% 6% 52%	2750
August	1st to 10th	Night	11% 6% 2 7% 5% 4 4 3 5% 8% 45%	2517
	11th to 20th	Night	11% 4 2 6% 4 4 5% 3 6% 7% 50%	2796
	21st to end	Night	12% 6% 2 6% 4 4 4 3 4 6% 49%	3476
September	1st to 10th	Night	9% 5% 2 6% 3 4 3 4 5% 6% 53%	1900
	11th to 20th	Night	12% 4 2 4 4 3 4 4 4 7% 51%	1990
	21st to end	Night	14% 6% 2 7% 3 3 3 3 5% 8% 44%	2090
October	1st to 10th	Night	15% 6% 2 5% 4 3 4 4 6% 7% 45%	2172
	11th to 20th	Night	16% 11% 3 8% 4 4 4 4 5% 6% 35%	2353
	21st to end	Night	20% 10% 3 6% 5% 4 4 3 5% 7% 32%	2717
November	1st to 10th	Night	15% 9% 3 7% 4 4 4 3 5% 7% 38%	2470
	11th to 20th	Night	14% 11% 3 9% 5% 5% 4 3 6% 7% 33%	2501
	21st to end	Night	14% 12% 4 8% 5% 6% 5% 4 5% 6% 32%	2660
December	1st to 10th	Night	13% 14% 5% 8% 6% 4 4 3 6% 6% 32%	2660
	11th to 20th	Night	13% 14% 5% 9% 6% 5% 5% 4 4 5% 30%	3279
	21st to end	Night	24% 20% 6% 8% 4 4 3 2 4 4 22%	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	55% 8% 13% 17% 6%	2528
	11th to 20th	Day	56% 9% 13% 16% 6% 1	2530
	21st to end	Day	62% 7% 14% 12% 4 1	2783
February	1st to 10th	Day	48% 6% 14% 19% 12% 1	1633
	11th to 20th	Day	47% 7% 13% 23% 9% 1	1806
	21st to end	Day	50% 6% 11% 20% 10% 2	1570
March	1st to 10th	Day	40% 6% 14% 21% 17% 2	3120
	11th to 20th	Day	47% 7% 14% 22% 9% 1	3266
	21st to end	Day	61% 6% 9% 15% 9%	4165
April	1st to 10th	Day	55% 6% 12% 17% 9% 1	2280
	11th to 20th	Day	52% 6% 9% 20% 11% 1	2254
	21st to end	Day	50% 7% 9% 18% 14% 2	2465
May	1st to 10th	Day	43% 8% 11% 22% 15% 1	4270
	11th to 20th	Day	38% 8% 12% 27% 14% 1	4403
	21st to end	Day	43% 9% 11% 19% 17% 2	4837
June	1st to 10th	Day	37% 8% 14% 24% 15% 2	2660
	11th to 20th	Day	43% 8% 14% 19% 15% 1	2660
	21st to end	Day	40% 9% 15% 23% 12% 1	2660
July	1st to 10th	Day	41% 7% 15% 24% 12% 1	4371
	11th to 20th	Day	29% 7% 12% 35% 15% 2	4365
	21st to end	Day	33% 7% 12% 29% 18% 1	4662
August	1st to 10th	Day	39% 9% 14% 24% 13% 1	4408
	11th to 20th	Day	35% 6% 16% 30% 12%	4071
	21st to end	Day	41% 8% 15% 21% 15% 1	4179
September	1st to 10th	Day	39% 7% 13% 27% 13% 1	2280
	11th to 20th	Day	36% 10% 18% 27% 8%	2171
	21st to end	Day	42% 8% 14% 27% 8%	2090
October	1st to 10th	Day	31% 5% 12% 29% 22%	3330
	11th to 20th	Day	50% 4 10% 23% 13%	3016
	21st to end	Day	51% 6% 14% 22% 7%	3081
November	1st to 10th	Day	45% 6% 12% 24% 11%	1708
	11th to 20th	Day	54% 8% 14% 16% 8%	1677
	21st to end	Day	51% 9% 16% 18% 4 1	1520
December	1st to 10th	Day	51% 8% 13% 22% 6%	1520
	11th to 20th	Day	57% 8% 12% 15% 7% 1	1915
	21st to end	Day	69% 6% 7% 13% 5%	2783
January	1st to 10th	Night	54% 6% 12% 19% 8% 1	4428
	11th to 20th	Night	59% 8% 12% 17% 4	4440
	21st to end	Night	60% 7% 13% 14% 5%	4884
February	1st to 10th	Night	51% 5% 11% 19% 12% 2	2546
	11th to 20th	Night	47% 7% 13% 22% 10% 2	2270
	21st to end	Night	52% 5% 13% 20% 9% 1	1884
March	1st to 10th	Night	39% 7% 19% 24% 10% 1	3733
	11th to 20th	Night	43% 7% 12% 26% 11% 1	3724
	21st to end	Night	54% 9% 11% 16% 10% 1	3466
April	1st to 10th	Night	53% 6% 10% 15% 14% 1	1900
	11th to 20th	Night	47% 5% 10% 22% 12% 3	1875
	21st to end	Night	47% 7% 11% 20% 13% 2	1713
May	1st to 10th	Night	43% 7% 11% 24% 13% 1	2690
	11th to 20th	Night	38% 9% 13% 25% 13% 1	2507
	21st to end	Night	43% 8% 14% 17% 12% 6%	2751
June	1st to 10th	Night	35% 7% 13% 28% 15% 2	1520
	11th to 20th	Night	42% 7% 12% 22% 15% 1	1520
	21st to end	Night	36% 7% 16% 27% 12% 2	1520
July	1st to 10th	Night	39% 7% 15% 23% 13% 3	2490
	11th to 20th	Night	23% 6% 19% 35% 15% 2	2482
	21st to end	Night	31% 7% 12% 27% 21% 1	2662
August	1st to 10th	Night	37% 7% 13% 22% 18% 2	2508
	11th to 20th	Night	33% 8% 14% 30% 14% 2	2822
	21st to end	Night	37% 6% 14% 25% 18% 1	3476
September	1st to 10th	Night	31% 7% 13% 32% 16%	1900
	11th to 20th	Night	32% 7% 15% 34% 11%	1990
	21st to end	Night	39% 6% 16% 28% 10% 1	2090
October	1st to 10th	Night	31% 5% 11% 35% 16% 2	3627
	11th to 20th	Night	39% 5% 13% 27% 15%	3902
	21st to end	Night	50% 5% 12% 24% 10%	4467
November	1st to 10th	Night	46% 6% 13% 23% 12%	2470
	11th to 20th	Night	50% 7% 14% 19% 10%	2501
	21st to end	Night	51% 7% 15% 21% 5% 1	2660
December	1st to 10th	Night	52% 7% 14% 20% 7%	2660
	11th to 20th	Night	55% 7% 12% 19% 7%	3281
	21st to end	Night	66% 6% 8% 15% 5%	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	20% 15% 34% 22% 8% 1	270
	11th to 20th	Day	24% 17% 33% 21% 4 1	270
	21st to end	Day	22% 13% 43% 18% 4	297
February	1st to 10th	Day	16% 24% 40% 14% 6% 1	270
	11th to 20th	Day	19% 27% 35% 14% 4	270
	21st to end	Day	24% 22% 43% 10% 1	225
March	1st to 10th	Day	17% 26% 43% 11% 3	270
	11th to 20th	Day	19% 20% 37% 16% 6%	298
	21st to end	Day	27% 18% 28% 19% 8%	506
April	1st to 10th	Day	26% 19% 31% 18% 6% 1	460
	11th to 20th	Day	27% 20% 27% 17% 8% 1	452
	21st to end	Day	25% 16% 28% 21% 8% 2	460
May	1st to 10th	Day	22% 21% 30% 17% 7% 2	548
	11th to 20th	Day	18% 17% 35% 20% 7% 3	675
	21st to end	Day	17% 16% 30% 24% 8% 5%	734
June	1st to 10th	Day	12% 17% 34% 24% 10% 3	680
	11th to 20th	Day	18% 13% 35% 22% 10% 2	680
	21st to end	Day	16% 12% 31% 28% 10% 4	680
July	1st to 10th	Day	9% 9% 31% 32% 15% 5%	671
	11th to 20th	Day	9% 10% 34% 27% 14% 6%	668
	21st to end	Day	7% 9% 34% 29% 15% 6%	739
August	1st to 10th	Day	9% 8% 31% 29% 18% 5%	676
	11th to 20th	Day	12% 8% 24% 28% 20% 8%	528
	21st to end	Day	16% 10% 23% 24% 20% 6%	539
September	1st to 10th	Day	16% 11% 26% 26% 14% 6%	490
	11th to 20th	Day	12% 8% 28% 32% 17% 3	490
	21st to end	Day	18% 15% 25% 26% 14% 3	490
October	1st to 10th	Day	21% 17% 30% 18% 13% 1	405
	11th to 20th	Day	25% 23% 32% 17% 3	300
	21st to end	Day	29% 20% 35% 13% 3	330
November	1st to 10th	Day	17% 20% 36% 18% 7% 1	282
	11th to 20th	Day	20% 25% 33% 15% 5% 1	270
	21st to end	Day	21% 21% 39% 13% 6%	270
December	1st to 10th	Day	18% 18% 39% 19% 5% 1	270
	11th to 20th	Day	24% 21% 37% 13% 4	270
	21st to end	Day	29% 20% 33% 14% 3	297
January	1st to 10th	Night	16% 12% 42% 24% 5%	950
	11th to 20th	Night	20% 13% 38% 22% 7% 1	950
	21st to end	Night	18% 10% 40% 25% 7% 1	1045
February	1st to 10th	Night	15% 13% 40% 25% 6%	950
	11th to 20th	Night	17% 16% 37% 24% 6%	794
	21st to end	Night	21% 14% 39% 23% 3	628
March	1st to 10th	Night	16% 13% 36% 28% 7%	760
	11th to 20th	Night	15% 16% 42% 21% 6%	751
	21st to end	Night	18% 11% 35% 29% 7% 1	627
April	1st to 10th	Night	22% 14% 35% 25% 5%	570
	11th to 20th	Night	26% 10% 30% 28% 6%	563
	21st to end	Night	20% 10% 32% 28% 8%	570
May	1st to 10th	Night	22% 11% 30% 30% 7% 1	570
	11th to 20th	Night	19% 11% 33% 30% 6% 1	561
	21st to end	Night	15% 7% 29% 35% 13%	617
June	1st to 10th	Night	13% 8% 30% 39% 10%	570
	11th to 20th	Night	18% 7% 28% 37% 10% 1	570
	21st to end	Night	14% 6% 26% 39% 13% 1	570
July	1st to 10th	Night	8% 4 25% 45% 19% 1	555
	11th to 20th	Night	9% 4 29% 39% 19%	552
	21st to end	Night	10% 4 29% 37% 18% 2	624
August	1st to 10th	Night	10% 3 26% 40% 19% 2	567
	11th to 20th	Night	10% 3 23% 38% 24% 2	564
	21st to end	Night	13% 6% 23% 38% 19% 1	627
September	1st to 10th	Night	11% 6% 26% 32% 21% 3	570
	11th to 20th	Night	13% 5% 30% 31% 19% 2	660
	21st to end	Night	17% 9% 29% 30% 15% 1	760
October	1st to 10th	Night	18% 11% 30% 27% 13% 1	760
	11th to 20th	Night	20% 13% 34% 24% 7%	760
	21st to end	Night	26% 11% 32% 24% 7%	836
November	1st to 10th	Night	20% 11% 36% 26% 6% 1	760
	11th to 20th	Night	20% 16% 37% 21% 6%	791
	21st to end	Night	21% 14% 34% 26% 5%	950
December	1st to 10th	Night	21% 14% 39% 21% 6% 1	950
	11th to 20th	Night	20% 13% 36% 24% 6% 1	950
	21st to end	Night	27% 11% 37% 21% 3	1045

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