Dinosaur Provincial Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Dinosaur Provincial Park clear sky chart from 2005-11-06 to 2025-04-26.

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	7% 8% 3 8% 5% 5% 5% 4 6% 8% 41%	117025
	Night	6% 8% 3 9% 6% 5% 5% 4 6% 8% 37%	120300
Transparency	Day	40% 6% 15% 27% 11% 2	116766
	Night	43% 6% 15% 24% 11% 1	120205
Seeing	Day	11% 7% 25% 31% 20% 6%	16020
	Night	11% 7% 29% 36% 15% 2	25389

By Month

Percentage Cloud Cover NW (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	5% 14% 6% 16% 9% 6% 6% 4 5% 7% 25%	3179
	11th to 20th	Day	5% 10% 4 9% 7% 5% 8% 7% 8% 9% 27%	3159
	21st to end	Day	3 9% 4 8% 4 5% 6% 5% 7% 9% 40%	3838
February	1st to 10th	Day	8% 14% 5% 12% 7% 6% 6% 5% 6% 7% 24%	1715
	11th to 20th	Day	7% 13% 5% 12% 7% 5% 6% 7% 8% 7% 24%	1755
	21st to end	Day	4 14% 4 12% 7% 6% 7% 4 6% 8% 28%	1498
March	1st to 10th	Day	4 8% 4 11% 7% 6% 5% 4 6% 9% 35%	4667
	11th to 20th	Day	6% 9% 4 9% 5% 5% 6% 5% 6% 8% 37%	4999
	21st to end	Day	7% 13% 5% 11% 6% 5% 5% 5% 7% 9% 27%	5486
April	1st to 10th	Day	8% 11% 3 10% 6% 6% 6% 4 6% 8% 33%	2452
	11th to 20th	Day	9% 11% 4 8% 5% 5% 5% 5% 6% 8% 33%	2570
	21st to end	Day	10% 8% 3 8% 6% 5% 5% 5% 7% 9% 33%	2537
May	1st to 10th	Day	18% 12% 3 7% 5% 4 4 4 6% 6% 31%	4355
	11th to 20th	Day	8% 7% 3 8% 5% 5% 6% 5% 8% 10% 35%	4620
	21st to end	Day	13% 9% 3 8% 6% 6% 6% 4 7% 8% 30%	5161
June	1st to 10th	Day	13% 7% 2 6% 5% 5% 5% 5% 7% 8% 37%	2850
	11th to 20th	Day	16% 7% 2 7% 5% 5% 5% 4 7% 9% 32%	2850
	21st to end	Day	8% 3 1 5% 4 4 4 5% 7% 10% 47%	2850
July	1st to 10th	Day	5% 4 2 5% 4 4 5% 4 6% 9% 52%	4740
	11th to 20th	Day	5% 4 2 5% 3 3 4 4 6% 8% 56%	4740
	21st to end	Day	3 2 1 2 2 2 3 3 5% 8% 69%	5138
August	1st to 10th	Day	5% 5% 2 5% 4 4 4 4 6% 8% 53%	4330
	11th to 20th	Day	5% 3 2 4 3 4 4 4 7% 10% 53%	4028
	21st to end	Day	7% 3 1 3 2 3 3 3 6% 8% 59%	4521
September	1st to 10th	Day	10% 6% 2 5% 3 3 4 3 5% 7% 53%	2366
	11th to 20th	Day	14% 6% 2 6% 4 4 3 2 5% 8% 46%	2109
	21st to end	Day	8% 7% 2 5% 4 3 4 4 6% 8% 50%	2090
October	1st to 10th	Day	6% 5% 3 8% 5% 5% 5% 5% 6% 6% 47%	3209
	11th to 20th	Day	5% 5% 2 5% 4 5% 5% 4 7% 9% 48%	3104
	21st to end	Day	8% 6% 2 6% 3 3 4 4 7% 8% 48%	3049
November	1st to 10th	Day	11% 13% 5% 10% 6% 6% 4 4 6% 6% 28%	1568
	11th to 20th	Day	5% 12% 4 10% 7% 6% 6% 4 6% 6% 35%	1600
	21st to end	Day	6% 12% 5% 10% 6% 6% 4 4 6% 9% 32%	1462
December	1st to 10th	Day	9% 13% 4 8% 7% 6% 6% 5% 7% 8% 28%	2290
	11th to 20th	Day	7% 12% 5% 13% 7% 6% 6% 4 6% 7% 27%	2642
	21st to end	Day	3 8% 4 11% 6% 5% 6% 4 6% 7% 41%	3498
January	1st to 10th	Night	4 12% 5% 13% 9% 7% 6% 4 7% 8% 25%	6766
	11th to 20th	Night	5% 9% 4 12% 7% 6% 6% 4 6% 8% 33%	6739
	21st to end	Night	3 9% 5% 11% 5% 5% 5% 4 6% 8% 40%	7161
February	1st to 10th	Night	6% 11% 4 10% 6% 7% 6% 5% 6% 7% 30%	2684
	11th to 20th	Night	6% 11% 4 11% 7% 6% 7% 5% 7% 7% 28%	2532
	21st to end	Night	4 10% 3 10% 6% 6% 6% 5% 8% 9% 33%	2130
March	1st to 10th	Night	3 7% 4 11% 6% 6% 6% 5% 7% 10% 34%	5214
	11th to 20th	Night	7% 8% 3 7% 5% 5% 6% 5% 9% 10% 36%	5000
	21st to end	Night	7% 15% 6% 13% 6% 7% 6% 5% 6% 8% 21%	5489
April	1st to 10th	Night	8% 10% 4 9% 6% 6% 6% 5% 6% 8% 32%	1946
	11th to 20th	Night	9% 11% 3 10% 6% 5% 5% 4 6% 8% 33%	1781
	21st to end	Night	10% 9% 3 6% 5% 4 6% 5% 7% 9% 37%	1759
May	1st to 10th	Night	21% 10% 4 8% 5% 4 4 4 4 6% 30%	2614
	11th to 20th	Night	7% 4 3 7% 5% 6% 7% 6% 10% 11% 35%	2273
	21st to end	Night	12% 8% 3 9% 7% 7% 6% 5% 7% 7% 28%	2414
June	1st to 10th	Night	15% 8% 2 6% 4 5% 5% 5% 9% 9% 33%	1330
	11th to 20th	Night	15% 6% 4 5% 5% 5% 6% 6% 8% 8% 32%	1330
	21st to end	Night	7% 4 3 5% 5% 5% 5% 4 6% 8% 49%	1330
July	1st to 10th	Night	4 5% 2 5% 4 5% 5% 5% 8% 9% 49%	2220
	11th to 20th	Night	5% 3 2 4 4 4 5% 4 6% 11% 51%	2220
	21st to end	Night	2 3 2 4 4 3 3 3 6% 9% 61%	2414
August	1st to 10th	Night	7% 4 2 6% 4 5% 5% 4 7% 9% 48%	2601
	11th to 20th	Night	4 4 2 6% 5% 5% 4 5% 8% 10% 46%	2811
	21st to end	Night	9% 3 1 3 2 3 4 3 5% 9% 59%	3146
September	1st to 10th	Night	9% 5% 2 5% 5% 4 5% 3 5% 8% 48%	1813
	11th to 20th	Night	12% 5% 2 5% 4 4 3 3 5% 7% 50%	2067
	21st to end	Night	7% 5% 2 6% 5% 3 4 4 6% 8% 50%	2090
October	1st to 10th	Night	6% 6% 2 7% 4 4 4 4 6% 9% 49%	3761
	11th to 20th	Night	4 4 2 6% 5% 4 5% 5% 6% 9% 49%	3824
	21st to end	Night	5% 8% 4 8% 5% 4 5% 4 6% 8% 44%	4478
November	1st to 10th	Night	10% 12% 3 9% 6% 5% 5% 4 6% 7% 34%	2730
	11th to 20th	Night	5% 10% 2 9% 7% 6% 6% 4 7% 9% 35%	2800
	21st to end	Night	6% 11% 4 10% 7% 6% 5% 5% 7% 9% 31%	2935
December	1st to 10th	Night	6% 12% 5% 11% 7% 6% 6% 5% 7% 7% 27%	4890
	11th to 20th	Night	7% 12% 5% 11% 7% 6% 5% 5% 6% 9% 27%	5550
	21st to end	Night	4 7% 3 10% 6% 5% 5% 4 6% 7% 42%	7458

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% 6% 12% 19% 6% 1	3179
	11th to 20th	Day	49% 7% 13% 15% 15% 1	3180
	21st to end	Day	38% 7% 22% 27% 6%	3838
February	1st to 10th	Day	57% 6% 12% 17% 7%	1715
	11th to 20th	Day	52% 8% 14% 17% 8%	1764
	21st to end	Day	52% 7% 12% 20% 10%	1498
March	1st to 10th	Day	44% 6% 14% 24% 11%	4667
	11th to 20th	Day	45% 5% 16% 23% 12%	5000
	21st to end	Day	52% 7% 17% 19% 5%	5486
April	1st to 10th	Day	46% 7% 15% 23% 9%	2452
	11th to 20th	Day	46% 6% 11% 27% 8% 2	2570
	21st to end	Day	45% 7% 14% 25% 8% 1	2537
May	1st to 10th	Day	52% 6% 11% 25% 6%	4355
	11th to 20th	Day	39% 8% 14% 26% 12%	4624
	21st to end	Day	48% 9% 12% 24% 6% 1	5162
June	1st to 10th	Day	43% 6% 15% 23% 11% 2	2850
	11th to 20th	Day	46% 8% 13% 23% 8% 2	2850
	21st to end	Day	29% 7% 21% 31% 9% 2	2850
July	1st to 10th	Day	27% 5% 18% 28% 17% 4	4666
	11th to 20th	Day	25% 4 17% 32% 18% 2	4659
	21st to end	Day	15% 3 11% 32% 26% 12%	4976
August	1st to 10th	Day	29% 4 13% 36% 15% 2	4312
	11th to 20th	Day	26% 5% 19% 39% 10% 1	4067
	21st to end	Day	24% 4 18% 38% 15% 2	4520
September	1st to 10th	Day	32% 4 14% 27% 16% 7%	2366
	11th to 20th	Day	38% 5% 14% 29% 12% 2	2109
	21st to end	Day	31% 5% 15% 31% 14% 3	2090
October	1st to 10th	Day	37% 4 17% 31% 9% 1	3209
	11th to 20th	Day	31% 4 18% 32% 13% 1	3104
	21st to end	Day	33% 4 12% 39% 11% 1	3049
November	1st to 10th	Day	54% 6% 12% 20% 7% 1	1568
	11th to 20th	Day	46% 7% 17% 23% 7%	1600
	21st to end	Day	48% 6% 17% 21% 7% 1	1462
December	1st to 10th	Day	52% 6% 21% 17% 3 1	2290
	11th to 20th	Day	56% 5% 17% 18% 4	2644
	21st to end	Day	42% 4 12% 27% 14% 1	3498
January	1st to 10th	Night	54% 6% 16% 18% 5% 1	6766
	11th to 20th	Night	49% 5% 14% 16% 15% 1	6780
	21st to end	Night	42% 6% 18% 28% 6%	7161
February	1st to 10th	Night	50% 7% 12% 20% 11% 1	2684
	11th to 20th	Night	51% 6% 12% 19% 11% 1	2533
	21st to end	Night	44% 7% 14% 24% 11% 1	2130
March	1st to 10th	Night	42% 5% 18% 25% 9%	5214
	11th to 20th	Night	40% 6% 16% 30% 7% 1	5000
	21st to end	Night	57% 9% 14% 15% 5%	5489
April	1st to 10th	Night	47% 7% 12% 21% 12% 1	1946
	11th to 20th	Night	48% 5% 12% 21% 12% 1	1781
	21st to end	Night	42% 6% 13% 26% 11% 2	1759
May	1st to 10th	Night	54% 6% 9% 21% 9%	2614
	11th to 20th	Night	35% 9% 15% 27% 12% 1	2273
	21st to end	Night	47% 11% 14% 21% 7% 1	2414
June	1st to 10th	Night	44% 6% 17% 22% 11% 1	1330
	11th to 20th	Night	44% 8% 14% 21% 11% 1	1330
	21st to end	Night	31% 6% 17% 31% 13% 1	1330
July	1st to 10th	Night	29% 5% 19% 24% 20% 2	2185
	11th to 20th	Night	27% 5% 15% 36% 15% 3	2178
	21st to end	Night	20% 4 8% 35% 23% 10%	2337
August	1st to 10th	Night	32% 5% 15% 30% 17% 2	2594
	11th to 20th	Night	31% 5% 16% 35% 12% 2	2838
	21st to end	Night	24% 4 14% 37% 19% 3	3146
September	1st to 10th	Night	33% 5% 12% 24% 18% 7%	1813
	11th to 20th	Night	34% 5% 14% 29% 14% 4	2067
	21st to end	Night	30% 6% 14% 31% 17% 2	2090
October	1st to 10th	Night	34% 4 14% 33% 15% 1	3761
	11th to 20th	Night	31% 4 16% 31% 16% 2	3824
	21st to end	Night	38% 5% 11% 37% 8%	4478
November	1st to 10th	Night	48% 6% 14% 21% 9% 1	2730
	11th to 20th	Night	43% 7% 18% 21% 10% 1	2800
	21st to end	Night	48% 7% 19% 19% 7% 1	2935
December	1st to 10th	Night	55% 5% 19% 16% 5%	4890
	11th to 20th	Night	53% 6% 23% 14% 3	5547
	21st to end	Night	39% 5% 12% 25% 17% 2	7458

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	8% 9% 29% 29% 19% 8%	200
	11th to 20th	Day	13% 5% 27% 36% 18% 3	200
	21st to end	Day	5% 8% 31% 36% 16% 5%	220
February	1st to 10th	Day	18% 9% 28% 33% 12% 2	257
	11th to 20th	Day	11% 5% 23% 40% 18% 3	300
	21st to end	Day	7% 7% 26% 34% 21% 5%	262
March	1st to 10th	Day	10% 9% 31% 30% 15% 6%	500
	11th to 20th	Day	10% 6% 31% 34% 14% 5%	500
	21st to end	Day	10% 9% 30% 28% 18% 5%	550
April	1st to 10th	Day	9% 12% 29% 31% 14% 4	500
	11th to 20th	Day	11% 12% 32% 30% 13% 2	492
	21st to end	Day	12% 11% 25% 33% 14% 5%	481
May	1st to 10th	Day	15% 8% 20% 29% 20% 7%	604
	11th to 20th	Day	12% 6% 21% 34% 21% 6%	675
	21st to end	Day	17% 6% 19% 28% 23% 7%	734
June	1st to 10th	Day	13% 10% 21% 33% 20% 3	680
	11th to 20th	Day	17% 8% 29% 27% 15% 3	680
	21st to end	Day	10% 5% 23% 33% 22% 8%	680
July	1st to 10th	Day	7% 5% 17% 36% 26% 9%	671
	11th to 20th	Day	10% 4 23% 31% 26% 6%	668
	21st to end	Day	5% 3 21% 32% 30% 9%	739
August	1st to 10th	Day	6% 5% 20% 36% 24% 9%	535
	11th to 20th	Day	8% 3 17% 33% 29% 10%	477
	21st to end	Day	8% 7% 22% 29% 24% 11%	539
September	1st to 10th	Day	12% 7% 23% 29% 24% 6%	490
	11th to 20th	Day	16% 6% 22% 29% 22% 5%	490
	21st to end	Day	12% 11% 32% 26% 16% 4	490
October	1st to 10th	Day	16% 5% 24% 29% 19% 7%	326
	11th to 20th	Day	9% 7% 34% 25% 23% 2	300
	21st to end	Day	15% 12% 28% 28% 15% 1	330
November	1st to 10th	Day	19% 9% 26% 30% 14% 1	300
	11th to 20th	Day	11% 12% 38% 26% 10% 3	300
	21st to end	Day	8% 7% 37% 29% 12% 7%	230
December	1st to 10th	Day	12% 4 33% 31% 18% 3	200
	11th to 20th	Day	10% 11% 37% 29% 12% 2	200
	21st to end	Day	10% 8% 22% 35% 19% 6%	220
January	1st to 10th	Night	8% 9% 33% 34% 14% 2	1000
	11th to 20th	Night	13% 9% 30% 35% 13% 2	1000
	21st to end	Night	11% 8% 31% 35% 13% 2	972
February	1st to 10th	Night	12% 8% 25% 36% 17% 3	800
	11th to 20th	Night	12% 7% 29% 39% 12% 1	784
	21st to end	Night	9% 5% 24% 37% 21% 4	660
March	1st to 10th	Night	8% 8% 31% 37% 14% 3	800
	11th to 20th	Night	10% 8% 32% 34% 14% 2	800
	21st to end	Night	14% 8% 26% 35% 16% 1	880
April	1st to 10th	Night	13% 10% 29% 32% 13% 3	656
	11th to 20th	Night	13% 8% 32% 36% 10% 1	593
	21st to end	Night	14% 8% 25% 37% 15% 1	587
May	1st to 10th	Night	16% 7% 23% 32% 19% 2	570
	11th to 20th	Night	9% 6% 29% 37% 18% 1	422
	21st to end	Night	21% 5% 21% 31% 20% 2	411
June	1st to 10th	Night	18% 8% 24% 31% 17% 2	380
	11th to 20th	Night	17% 6% 28% 32% 16% 1	380
	21st to end	Night	9% 6% 24% 36% 22% 3	380
July	1st to 10th	Night	8% 4 21% 46% 21% 1	370
	11th to 20th	Night	8% 4 25% 42% 19% 1	368
	21st to end	Night	4 5% 21% 43% 24% 3	416
August	1st to 10th	Night	8% 3 23% 40% 24% 2	462
	11th to 20th	Night	9% 4 21% 41% 24% 1	564
	21st to end	Night	12% 4 22% 37% 23% 2	627
September	1st to 10th	Night	12% 4 22% 45% 16% 2	570
	11th to 20th	Night	14% 4 22% 41% 17% 1	737
	21st to end	Night	11% 6% 30% 35% 16% 2	760
October	1st to 10th	Night	13% 5% 28% 39% 13% 2	760
	11th to 20th	Night	9% 8% 31% 35% 15% 2	760
	21st to end	Night	12% 9% 31% 36% 12%	845
November	1st to 10th	Night	17% 8% 33% 32% 9% 1	975
	11th to 20th	Night	10% 11% 38% 28% 11% 2	1000
	21st to end	Night	11% 8% 32% 36% 12% 1	1000
December	1st to 10th	Night	12% 7% 30% 34% 14% 3	1000
	11th to 20th	Night	10% 8% 34% 34% 13% 2	1000
	21st to end	Night	10% 6% 32% 35% 14% 2	1100

Page generated at 2025-04-23 07:25:02. Version ac07

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