Hartman Creek State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hartman Creek State Park clear sky chart from 2005-11-06 to 2024-11-25.

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% 8% 3 7% 5% 4 5% 4 6% 7% 38%	101691
	Night	13% 9% 3 7% 5% 4 4 4 5% 7% 39%	97886
Transparency	Day	43% 7% 13% 24% 12% 1	105209
	Night	44% 7% 12% 23% 13% 1	102508
Seeing	Day	15% 11% 30% 26% 14% 4	16038
	Night	16% 9% 33% 30% 11% 1	25916

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% 14% 7% 11% 5% 5% 4 3 4 5% 30%	2527
	11th to 20th	Day	10% 13% 5% 11% 6% 7% 8% 6% 6% 7% 21%	2530
	21st to end	Day	16% 17% 7% 11% 5% 5% 4 3 4 5% 23%	2819
February	1st to 10th	Day	9% 11% 6% 10% 5% 4 5% 3 6% 6% 34%	1710
	11th to 20th	Day	10% 12% 4 7% 5% 4 5% 4 5% 7% 37%	1765
	21st to end	Day	11% 11% 4 10% 5% 5% 4 3 6% 7% 33%	1570
March	1st to 10th	Day	13% 8% 3 6% 4 3 3 3 5% 6% 48%	3120
	11th to 20th	Day	9% 8% 3 9% 4 4 4 3 5% 8% 44%	3338
	21st to end	Day	21% 12% 3 9% 5% 4 4 3 4 5% 30%	4129
April	1st to 10th	Day	16% 13% 3 8% 5% 4 5% 3 5% 6% 32%	2280
	11th to 20th	Day	19% 10% 3 7% 5% 4 5% 4 4 5% 34%	2254
	21st to end	Day	19% 10% 3 8% 5% 4 5% 4 5% 6% 33%	2384
May	1st to 10th	Day	15% 6% 2 7% 5% 4 5% 4 5% 6% 40%	4291
	11th to 20th	Day	15% 5% 2 6% 4 3 4 3 6% 7% 46%	4399
	21st to end	Day	15% 7% 3 7% 5% 5% 5% 4 5% 6% 38%	4824
June	1st to 10th	Day	12% 5% 2 6% 5% 4 4 4 6% 8% 44%	2660
	11th to 20th	Day	14% 6% 2 6% 5% 5% 5% 3 7% 9% 39%	2660
	21st to end	Day	11% 6% 2 7% 4 4 6% 4 6% 9% 41%	2660
July	1st to 10th	Day	12% 5% 2 7% 4 5% 6% 4 8% 10% 37%	4440
	11th to 20th	Day	5% 2 1 4 4 5% 5% 5% 8% 11% 51%	4440
	21st to end	Day	8% 6% 2 7% 5% 5% 5% 4 6% 7% 45%	4813
August	1st to 10th	Day	10% 4 2 7% 5% 5% 5% 5% 6% 8% 43%	4423
	11th to 20th	Day	13% 4 2 4 4 5% 5% 3 6% 9% 45%	3892
	21st to end	Day	11% 6% 3 7% 5% 5% 5% 5% 6% 8% 41%	4180
September	1st to 10th	Day	12% 6% 3 6% 4 4 4 4 6% 7% 45%	2280
	11th to 20th	Day	12% 5% 2 5% 4 4 4 3 6% 7% 48%	2214
	21st to end	Day	12% 6% 3 8% 5% 4 4 4 6% 7% 41%	2090
October	1st to 10th	Day	14% 7% 2 6% 5% 5% 3 3 5% 7% 43%	1941
	11th to 20th	Day	17% 11% 3 8% 4 4 4 3 5% 7% 33%	1900
	21st to end	Day	16% 10% 3 8% 5% 4 4 3 4 6% 38%	1881
November	1st to 10th	Day	13% 8% 2 6% 5% 4 4 3 5% 6% 43%	1762
	11th to 20th	Day	12% 12% 4 8% 6% 6% 5% 4 6% 5% 31%	1742
	21st to end	Day	15% 10% 4 8% 5% 4 4 4 4 7% 35%	1552
December	1st to 10th	Day	12% 12% 5% 9% 6% 5% 5% 4 6% 6% 30%	1520
	11th to 20th	Day	13% 13% 4 9% 6% 6% 5% 3 6% 7% 28%	1918
	21st to end	Day	21% 20% 6% 11% 5% 4 4 2 4 4 19%	2783
January	1st to 10th	Night	13% 13% 8% 11% 4 3 3 3 3 4 34%	4428
	11th to 20th	Night	12% 11% 5% 12% 7% 7% 8% 6% 6% 5% 22%	4440
	21st to end	Night	14% 19% 7% 11% 5% 4 4 3 4 5% 23%	4843
February	1st to 10th	Night	9% 13% 5% 10% 5% 5% 4 4 5% 5% 35%	2470
	11th to 20th	Night	10% 9% 4 7% 5% 5% 5% 4 5% 5% 40%	2301
	21st to end	Night	16% 11% 3 8% 5% 3 4 4 4 6% 35%	1884
March	1st to 10th	Night	14% 8% 2 5% 4 3 4 3 5% 8% 44%	3733
	11th to 20th	Night	10% 8% 2 7% 5% 5% 5% 4 6% 6% 42%	3650
	21st to end	Night	21% 10% 3 9% 5% 5% 5% 3 4 5% 30%	3501
April	1st to 10th	Night	19% 10% 3 7% 5% 3 4 3 5% 6% 36%	1900
	11th to 20th	Night	20% 7% 2 6% 4 3 4 3 6% 6% 38%	1875
	21st to end	Night	17% 8% 3 5% 5% 4 4 4 5% 7% 38%	1796
May	1st to 10th	Night	15% 8% 2 8% 5% 5% 5% 4 5% 7% 35%	2608
	11th to 20th	Night	12% 5% 2 5% 4 3 4 4 6% 8% 47%	2506
	21st to end	Night	15% 7% 3 7% 5% 4 4 3 5% 6% 41%	2743
June	1st to 10th	Night	9% 4 2 7% 5% 4 5% 5% 5% 9% 46%	1520
	11th to 20th	Night	11% 6% 3 6% 4 5% 3 5% 6% 8% 42%	1520
	21st to end	Night	8% 6% 2 5% 5% 3 4 4 7% 8% 48%	1520
July	1st to 10th	Night	14% 5% 2 5% 3 5% 4 4 6% 9% 43%	2530
	11th to 20th	Night	5% 3 2 4 4 4 4 5% 6% 8% 57%	2530
	21st to end	Night	7% 6% 2 6% 4 4 4 3 6% 9% 49%	2750
August	1st to 10th	Night	11% 5% 1 5% 4 4 4 4 5% 7% 49%	2517
	11th to 20th	Night	10% 6% 2 7% 4 4 5% 3 6% 8% 44%	2939
	21st to end	Night	11% 5% 2 5% 4 4 4 3 6% 7% 48%	3476
September	1st to 10th	Night	10% 4 2 4 4 3 3 3 6% 7% 54%	1900
	11th to 20th	Night	13% 4 1 5% 3 4 3 3 5% 6% 53%	1946
	21st to end	Night	12% 6% 2 6% 4 4 4 4 4 7% 48%	2090
October	1st to 10th	Night	12% 6% 2 6% 4 3 4 3 5% 7% 49%	2236
	11th to 20th	Night	15% 7% 2 7% 4 4 4 4 5% 7% 40%	2280
	21st to end	Night	17% 9% 3 8% 4 4 4 3 5% 6% 35%	2717
November	1st to 10th	Night	14% 8% 3 5% 4 3 3 3 5% 7% 45%	2536
	11th to 20th	Night	14% 11% 4 8% 5% 5% 4 3 5% 6% 35%	2655
	21st to end	Night	15% 10% 3 6% 5% 5% 4 3 6% 7% 37%	2723
December	1st to 10th	Night	12% 13% 3 9% 5% 4 4 4 6% 8% 32%	2660
	11th to 20th	Night	13% 14% 5% 9% 6% 5% 4 3 5% 6% 30%	3279
	21st to end	Night	22% 17% 5% 9% 4 3 4 3 4 5% 23%	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	57% 7% 13% 16% 7% 1	2528
	11th to 20th	Day	59% 9% 11% 16% 5%	2530
	21st to end	Day	64% 6% 11% 14% 4	2819
February	1st to 10th	Day	49% 6% 13% 20% 11% 1	1710
	11th to 20th	Day	46% 7% 12% 24% 9% 2	1774
	21st to end	Day	50% 7% 13% 19% 10% 2	1570
March	1st to 10th	Day	38% 5% 13% 24% 18% 3	3120
	11th to 20th	Day	37% 7% 13% 27% 14% 2	3338
	21st to end	Day	56% 6% 9% 20% 7% 1	4129
April	1st to 10th	Day	52% 8% 11% 19% 10% 1	2280
	11th to 20th	Day	51% 7% 8% 20% 12% 2	2254
	21st to end	Day	51% 7% 11% 19% 10% 2	2384
May	1st to 10th	Day	41% 8% 12% 24% 15% 1	4330
	11th to 20th	Day	36% 7% 11% 32% 13% 1	4403
	21st to end	Day	43% 9% 10% 22% 16% 1	4837
June	1st to 10th	Day	36% 7% 14% 27% 15% 1	2660
	11th to 20th	Day	40% 8% 13% 25% 13% 1	2660
	21st to end	Day	38% 8% 15% 25% 12% 2	2660
July	1st to 10th	Day	41% 7% 16% 26% 9% 1	4371
	11th to 20th	Day	23% 8% 17% 35% 15% 2	4365
	21st to end	Day	36% 7% 13% 22% 20% 2	4662
August	1st to 10th	Day	37% 7% 16% 26% 13% 1	4408
	11th to 20th	Day	33% 8% 13% 34% 11%	3932
	21st to end	Day	39% 6% 14% 27% 14% 1	4179
September	1st to 10th	Day	36% 7% 14% 25% 16% 1	2280
	11th to 20th	Day	34% 8% 17% 30% 10% 1	2214
	21st to end	Day	40% 8% 13% 28% 11%	2090
October	1st to 10th	Day	25% 4 8% 38% 24% 1	3227
	11th to 20th	Day	40% 5% 10% 27% 17% 1	3140
	21st to end	Day	41% 4 15% 29% 11% 1	3081
November	1st to 10th	Day	41% 6% 14% 23% 15% 1	1762
	11th to 20th	Day	52% 7% 12% 19% 9% 1	1742
	21st to end	Day	49% 7% 15% 22% 6% 1	1552
December	1st to 10th	Day	52% 7% 14% 20% 6% 1	1520
	11th to 20th	Day	54% 7% 15% 14% 8% 2	1915
	21st to end	Day	68% 6% 7% 13% 6%	2783
January	1st to 10th	Night	55% 6% 10% 21% 9% 1	4428
	11th to 20th	Night	60% 7% 11% 15% 7%	4440
	21st to end	Night	63% 6% 9% 16% 6%	4843
February	1st to 10th	Night	50% 5% 11% 21% 10% 2	2470
	11th to 20th	Night	45% 7% 11% 24% 11% 2	2302
	21st to end	Night	49% 6% 13% 19% 10% 2	1884
March	1st to 10th	Night	39% 7% 13% 27% 11% 3	3733
	11th to 20th	Night	40% 7% 10% 25% 16% 2	3650
	21st to end	Night	55% 7% 8% 19% 9% 1	3501
April	1st to 10th	Night	49% 6% 9% 17% 17% 1	1900
	11th to 20th	Night	45% 7% 9% 21% 14% 3	1875
	21st to end	Night	44% 8% 12% 21% 14% 1	1796
May	1st to 10th	Night	44% 10% 15% 15% 16%	2634
	11th to 20th	Night	33% 9% 14% 27% 16% 1	2507
	21st to end	Night	42% 8% 12% 19% 18% 2	2751
June	1st to 10th	Night	33% 9% 14% 26% 17% 1	1520
	11th to 20th	Night	38% 8% 12% 24% 16% 1	1520
	21st to end	Night	32% 8% 17% 27% 13% 4	1520
July	1st to 10th	Night	38% 6% 17% 21% 14% 4	2490
	11th to 20th	Night	23% 7% 16% 34% 18% 2	2482
	21st to end	Night	31% 7% 13% 25% 21% 2	2662
August	1st to 10th	Night	34% 6% 14% 27% 17% 1	2508
	11th to 20th	Night	35% 8% 14% 28% 14% 1	2965
	21st to end	Night	34% 6% 16% 22% 20% 2	3476
September	1st to 10th	Night	29% 7% 12% 30% 21% 1	1900
	11th to 20th	Night	32% 6% 13% 34% 15% 1	1946
	21st to end	Night	34% 7% 12% 30% 15% 1	2090
October	1st to 10th	Night	26% 4 7% 37% 23% 2	3730
	11th to 20th	Night	31% 6% 12% 31% 19% 1	3779
	21st to end	Night	46% 4 10% 23% 15%	4467
November	1st to 10th	Night	39% 6% 13% 25% 15% 2	2536
	11th to 20th	Night	49% 6% 14% 18% 12% 1	2655
	21st to end	Night	47% 7% 16% 22% 7% 1	2723
December	1st to 10th	Night	50% 7% 15% 20% 6% 1	2660
	11th to 20th	Night	55% 7% 12% 18% 7% 1	3281
	21st to end	Night	63% 7% 10% 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	16% 11% 33% 27% 11% 2	270
	11th to 20th	Day	18% 12% 37% 24% 8% 1	270
	21st to end	Day	18% 9% 38% 28% 6%	297
February	1st to 10th	Day	13% 16% 38% 25% 6% 2	270
	11th to 20th	Day	17% 21% 36% 19% 7%	270
	21st to end	Day	16% 18% 44% 20% 2	225
March	1st to 10th	Day	19% 14% 40% 22% 5%	270
	11th to 20th	Day	20% 17% 31% 21% 9% 2	270
	21st to end	Day	25% 12% 30% 22% 9% 2	483
April	1st to 10th	Day	24% 15% 32% 23% 5%	460
	11th to 20th	Day	25% 16% 29% 19% 9% 3	452
	21st to end	Day	21% 15% 29% 21% 12% 2	460
May	1st to 10th	Day	18% 12% 33% 27% 9% 1	582
	11th to 20th	Day	18% 12% 31% 25% 12% 3	675
	21st to end	Day	17% 9% 29% 27% 13% 6%	734
June	1st to 10th	Day	11% 8% 32% 28% 16% 5%	680
	11th to 20th	Day	16% 9% 30% 28% 14% 5%	680
	21st to end	Day	13% 9% 29% 30% 15% 4	680
July	1st to 10th	Day	8% 4 20% 31% 26% 11%	671
	11th to 20th	Day	8% 6% 26% 32% 18% 9%	668
	21st to end	Day	7% 4 25% 33% 23% 7%	739
August	1st to 10th	Day	8% 4 27% 30% 22% 9%	676
	11th to 20th	Day	13% 4 20% 26% 26% 10%	557
	21st to end	Day	12% 7% 23% 28% 23% 8%	539
September	1st to 10th	Day	14% 6% 26% 26% 20% 8%	490
	11th to 20th	Day	12% 4 21% 34% 21% 8%	490
	21st to end	Day	15% 12% 26% 25% 17% 4	490
October	1st to 10th	Day	17% 12% 28% 23% 17% 4	341
	11th to 20th	Day	20% 19% 32% 21% 8%	300
	21st to end	Day	21% 15% 37% 21% 5% 1	330
November	1st to 10th	Day	15% 17% 35% 23% 10% 1	300
	11th to 20th	Day	16% 21% 37% 20% 6%	300
	21st to end	Day	21% 13% 43% 18% 5%	282
December	1st to 10th	Day	16% 16% 44% 19% 6% 1	270
	11th to 20th	Day	21% 17% 36% 18% 6% 1	270
	21st to end	Day	26% 19% 37% 14% 4	297
January	1st to 10th	Night	17% 13% 37% 26% 7% 1	950
	11th to 20th	Night	18% 12% 37% 26% 5% 1	950
	21st to end	Night	18% 11% 37% 28% 7%	1045
February	1st to 10th	Night	14% 12% 39% 28% 6%	950
	11th to 20th	Night	15% 12% 42% 25% 7%	826
	21st to end	Night	21% 14% 37% 23% 4	628
March	1st to 10th	Night	17% 12% 34% 27% 9% 1	760
	11th to 20th	Night	14% 13% 39% 24% 8% 1	675
	21st to end	Night	21% 9% 30% 31% 7% 1	627
April	1st to 10th	Night	22% 10% 39% 24% 5%	570
	11th to 20th	Night	22% 10% 32% 29% 6% 1	563
	21st to end	Night	20% 9% 33% 31% 7% 1	570
May	1st to 10th	Night	21% 8% 34% 30% 6%	570
	11th to 20th	Night	18% 8% 32% 33% 7% 1	561
	21st to end	Night	15% 5% 25% 37% 17%	617
June	1st to 10th	Night	9% 6% 31% 41% 12% 1	570
	11th to 20th	Night	14% 5% 32% 37% 10% 1	570
	21st to end	Night	10% 5% 26% 42% 16% 1	570
July	1st to 10th	Night	7% 3 22% 43% 23% 2	555
	11th to 20th	Night	8% 5% 21% 42% 23% 2	552
	21st to end	Night	7% 2 23% 45% 22% 2	624
August	1st to 10th	Night	9% 3 17% 45% 25% 2	567
	11th to 20th	Night	9% 3 20% 35% 30% 3	564
	21st to end	Night	11% 3 21% 41% 23% 2	627
September	1st to 10th	Night	11% 5% 24% 37% 19% 5%	570
	11th to 20th	Night	13% 4 26% 31% 23% 3	616
	21st to end	Night	13% 8% 27% 34% 17% 1	760
October	1st to 10th	Night	13% 8% 30% 29% 18% 1	760
	11th to 20th	Night	18% 12% 33% 29% 8%	760
	21st to end	Night	21% 12% 32% 28% 7% 1	836
November	1st to 10th	Night	18% 10% 36% 26% 9% 1	780
	11th to 20th	Night	18% 14% 39% 23% 5%	855
	21st to end	Night	20% 14% 36% 24% 6% 1	973
December	1st to 10th	Night	18% 12% 41% 22% 6%	950
	11th to 20th	Night	21% 12% 37% 24% 5% 1	950
	21st to end	Night	28% 11% 36% 22% 4	1045

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