Regina
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Regina clear sky chart from 2005-11-06 to 2024-11-04.

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	9% 8% 3 8% 5% 5% 5% 4 6% 8% 39%	105520
	Night	8% 8% 3 9% 6% 5% 5% 4 6% 8% 38%	102094
Transparency	Day	42% 7% 16% 25% 9% 1	105278
	Night	42% 7% 16% 24% 10% 1	101982
Seeing	Day	12% 9% 30% 29% 15% 3	16028
	Night	12% 7% 31% 35% 13% 1	25463

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	7% 13% 5% 14% 8% 7% 8% 6% 6% 6% 20%	2219
	11th to 20th	Day	4 8% 3 11% 10% 10% 11% 9% 9% 7% 17%	2489
	21st to end	Day	6% 12% 5% 12% 6% 7% 6% 4 5% 6% 32%	2794
February	1st to 10th	Day	7% 14% 6% 14% 7% 8% 7% 5% 5% 7% 20%	1562
	11th to 20th	Day	8% 13% 5% 9% 7% 8% 9% 6% 7% 5% 24%	1665
	21st to end	Day	5% 11% 5% 13% 12% 7% 7% 5% 7% 6% 23%	1537
March	1st to 10th	Day	7% 13% 6% 12% 8% 6% 8% 4 5% 7% 23%	3130
	11th to 20th	Day	4 11% 6% 12% 6% 4 4 4 6% 8% 35%	3318
	21st to end	Day	7% 10% 5% 13% 6% 5% 5% 5% 6% 7% 32%	4124
April	1st to 10th	Day	7% 8% 3 8% 5% 5% 5% 5% 9% 9% 37%	2280
	11th to 20th	Day	13% 13% 4 10% 6% 6% 4 4 6% 7% 28%	2282
	21st to end	Day	13% 10% 3 6% 6% 4 5% 3 5% 7% 36%	2619
May	1st to 10th	Day	18% 11% 3 7% 4 3 4 3 5% 7% 36%	4430
	11th to 20th	Day	10% 7% 2 7% 6% 6% 5% 5% 7% 8% 36%	4388
	21st to end	Day	14% 6% 2 7% 6% 6% 5% 4 7% 8% 34%	4947
June	1st to 10th	Day	15% 5% 3 6% 5% 4 4 5% 6% 8% 37%	2940
	11th to 20th	Day	18% 8% 3 7% 5% 5% 6% 4 5% 7% 33%	3040
	21st to end	Day	10% 6% 1 5% 5% 5% 5% 4 7% 9% 42%	3040
July	1st to 10th	Day	6% 3 2 6% 5% 5% 6% 5% 8% 10% 45%	4914
	11th to 20th	Day	5% 3 1 4 3 5% 5% 4 6% 10% 52%	4585
	21st to end	Day	4 2 1 4 3 3 4 4 6% 9% 60%	4802
August	1st to 10th	Day	9% 5% 2 5% 4 4 5% 3 6% 8% 50%	4412
	11th to 20th	Day	6% 4 2 5% 4 4 4 4 7% 10% 50%	4343
	21st to end	Day	9% 4 2 6% 3 3 4 3 5% 7% 54%	4257
September	1st to 10th	Day	11% 5% 3 5% 4 3 5% 3 5% 7% 49%	2280
	11th to 20th	Day	12% 8% 3 6% 4 4 4 3 5% 8% 44%	2263
	21st to end	Day	13% 5% 2 5% 4 3 4 3 5% 8% 48%	2067
October	1st to 10th	Day	9% 8% 2 6% 5% 5% 5% 4 6% 7% 42%	3170
	11th to 20th	Day	7% 7% 2 5% 3 3 4 4 7% 10% 49%	3006
	21st to end	Day	7% 10% 4 9% 5% 4 4 4 6% 8% 38%	3091
November	1st to 10th	Day	12% 16% 4 9% 7% 5% 4 4 5% 5% 30%	1592
	11th to 20th	Day	7% 12% 4 14% 8% 7% 5% 4 6% 6% 28%	1520
	21st to end	Day	9% 13% 6% 10% 6% 6% 6% 4 6% 7% 28%	1361
December	1st to 10th	Day	7% 13% 5% 15% 9% 6% 7% 5% 6% 6% 21%	1330
	11th to 20th	Day	7% 16% 6% 14% 8% 7% 6% 6% 6% 6% 19%	1633
	21st to end	Day	5% 8% 5% 8% 6% 5% 5% 4 4 6% 45%	2090
January	1st to 10th	Night	4 13% 6% 13% 8% 6% 6% 5% 7% 8% 26%	4726
	11th to 20th	Night	4 8% 4 14% 11% 11% 10% 6% 6% 5% 21%	4414
	21st to end	Night	6% 12% 4 10% 6% 7% 5% 5% 6% 7% 32%	4873
February	1st to 10th	Night	8% 11% 5% 11% 7% 7% 7% 5% 7% 7% 24%	2636
	11th to 20th	Night	5% 11% 4 11% 7% 6% 8% 5% 7% 7% 27%	2402
	21st to end	Night	4 8% 4 12% 8% 7% 6% 4 7% 9% 31%	1916
March	1st to 10th	Night	7% 11% 5% 14% 8% 6% 5% 5% 5% 7% 28%	3734
	11th to 20th	Night	5% 11% 4 8% 6% 6% 6% 5% 6% 9% 35%	3655
	21st to end	Night	6% 10% 4 15% 7% 6% 5% 4 5% 7% 31%	3519
April	1st to 10th	Night	7% 9% 2 6% 4 5% 5% 3 8% 8% 43%	1900
	11th to 20th	Night	13% 12% 4 8% 4 5% 4 4 6% 8% 33%	1849
	21st to end	Night	13% 8% 3 8% 5% 4 5% 5% 6% 8% 34%	1558
May	1st to 10th	Night	19% 13% 3 7% 5% 4 3 3 5% 6% 33%	2540
	11th to 20th	Night	12% 6% 3 6% 4 4 5% 4 6% 8% 41%	2518
	21st to end	Night	14% 6% 3 6% 4 5% 5% 4 6% 8% 40%	2639
June	1st to 10th	Night	12% 5% 2 4 4 3 4 5% 7% 8% 45%	1235
	11th to 20th	Night	15% 6% 3 5% 4 3 5% 4 6% 8% 41%	1140
	21st to end	Night	9% 5% 2 5% 4 4 4 4 7% 9% 46%	1140
July	1st to 10th	Night	7% 4 1 4 4 4 4 4 7% 12% 50%	2042
	11th to 20th	Night	5% 3 1 4 4 3 4 3 6% 8% 58%	2380
	21st to end	Night	3 3 1 3 2 3 3 4 5% 7% 66%	2762
August	1st to 10th	Night	7% 4 2 5% 3 3 4 4 5% 7% 56%	2528
	11th to 20th	Night	4 3 1 5% 4 4 5% 4 7% 10% 53%	2496
	21st to end	Night	6% 4 2 5% 4 4 4 4 5% 8% 54%	3406
September	1st to 10th	Night	9% 4 1 5% 4 4 5% 3 6% 7% 53%	1900
	11th to 20th	Night	10% 6% 2 6% 4 4 5% 3 5% 8% 49%	1916
	21st to end	Night	10% 6% 2 5% 4 3 4 4 6% 6% 50%	2109
October	1st to 10th	Night	10% 7% 3 6% 3 4 4 3 5% 8% 47%	3800
	11th to 20th	Night	6% 6% 2 5% 4 4 4 4 6% 10% 50%	3891
	21st to end	Night	8% 8% 3 8% 5% 4 5% 4 5% 7% 43%	4467
November	1st to 10th	Night	15% 13% 4 9% 6% 4 5% 3 4 6% 31%	2557
	11th to 20th	Night	8% 12% 4 12% 8% 6% 6% 4 5% 7% 28%	2660
	21st to end	Night	8% 12% 5% 11% 6% 4 5% 4 5% 8% 32%	2816
December	1st to 10th	Night	7% 12% 4 13% 9% 7% 6% 4 5% 6% 26%	2850
	11th to 20th	Night	8% 13% 6% 14% 8% 6% 6% 5% 5% 6% 23%	3558
	21st to end	Night	5% 7% 3 8% 5% 5% 5% 4 7% 7% 43%	5562

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	61% 8% 14% 12% 4	2219
	11th to 20th	Day	59% 8% 17% 11% 4	2513
	21st to end	Day	52% 6% 15% 22% 4	2794
February	1st to 10th	Day	62% 7% 11% 15% 6%	1562
	11th to 20th	Day	58% 6% 11% 14% 10% 1	1674
	21st to end	Day	57% 8% 13% 13% 8%	1537
March	1st to 10th	Day	57% 7% 16% 16% 4	3130
	11th to 20th	Day	46% 9% 22% 18% 5%	3319
	21st to end	Day	49% 8% 15% 17% 10% 2	4124
April	1st to 10th	Day	39% 9% 18% 23% 10% 1	2280
	11th to 20th	Day	55% 7% 12% 18% 6% 2	2282
	21st to end	Day	47% 6% 17% 22% 7% 1	2619
May	1st to 10th	Day	47% 6% 15% 23% 8%	4430
	11th to 20th	Day	39% 10% 14% 23% 13%	4392
	21st to end	Day	41% 9% 15% 26% 7%	4947
June	1st to 10th	Day	42% 7% 16% 25% 9% 1	2940
	11th to 20th	Day	50% 8% 13% 19% 10% 1	3040
	21st to end	Day	35% 10% 18% 27% 9%	3040
July	1st to 10th	Day	30% 10% 24% 28% 7%	4839
	11th to 20th	Day	25% 8% 17% 37% 13%	4505
	21st to end	Day	20% 6% 14% 40% 16% 3	4651
August	1st to 10th	Day	31% 7% 19% 25% 16% 1	4396
	11th to 20th	Day	28% 7% 18% 37% 10% 1	4385
	21st to end	Day	30% 6% 15% 38% 11% 1	4256
September	1st to 10th	Day	33% 6% 15% 29% 15% 2	2280
	11th to 20th	Day	39% 5% 15% 27% 11% 2	2263
	21st to end	Day	34% 5% 15% 31% 13% 2	2067
October	1st to 10th	Day	39% 5% 16% 29% 10% 1	3170
	11th to 20th	Day	30% 4 17% 36% 10% 2	3006
	21st to end	Day	43% 5% 17% 27% 7%	3091
November	1st to 10th	Day	56% 7% 15% 16% 7%	1592
	11th to 20th	Day	55% 7% 14% 16% 7% 1	1520
	21st to end	Day	55% 9% 17% 16% 4	1361
December	1st to 10th	Day	61% 6% 12% 14% 6%	1330
	11th to 20th	Day	62% 9% 16% 10% 3	1634
	21st to end	Day	39% 5% 12% 24% 13% 7%	2090
January	1st to 10th	Night	53% 8% 17% 17% 4	4726
	11th to 20th	Night	61% 7% 16% 13% 3	4452
	21st to end	Night	50% 8% 17% 21% 4	4873
February	1st to 10th	Night	56% 6% 13% 18% 7%	2636
	11th to 20th	Night	51% 7% 14% 18% 10% 1	2403
	21st to end	Night	48% 7% 16% 21% 8%	1916
March	1st to 10th	Night	51% 7% 20% 18% 4	3734
	11th to 20th	Night	42% 8% 24% 20% 6%	3655
	21st to end	Night	51% 6% 13% 19% 10%	3519
April	1st to 10th	Night	36% 6% 15% 26% 16% 1	1900
	11th to 20th	Night	49% 5% 12% 21% 10% 3	1849
	21st to end	Night	45% 8% 11% 25% 11% 1	1558
May	1st to 10th	Night	50% 6% 11% 21% 11% 1	2540
	11th to 20th	Night	37% 8% 13% 22% 16% 3	2518
	21st to end	Night	37% 10% 15% 29% 9% 1	2639
June	1st to 10th	Night	33% 7% 15% 29% 14% 2	1235
	11th to 20th	Night	40% 8% 18% 20% 13% 1	1140
	21st to end	Night	33% 8% 19% 30% 10% 1	1140
July	1st to 10th	Night	25% 9% 30% 29% 7%	2008
	11th to 20th	Night	23% 7% 13% 39% 16% 2	2337
	21st to end	Night	17% 5% 15% 40% 17% 6%	2674
August	1st to 10th	Night	26% 7% 20% 30% 16% 1	2520
	11th to 20th	Night	25% 7% 17% 38% 12% 1	2520
	21st to end	Night	28% 6% 16% 36% 13% 2	3406
September	1st to 10th	Night	30% 7% 11% 29% 21% 3	1900
	11th to 20th	Night	33% 7% 16% 28% 16% 1	1916
	21st to end	Night	34% 6% 13% 30% 15% 2	2109
October	1st to 10th	Night	36% 4 16% 32% 9% 2	3800
	11th to 20th	Night	30% 4 15% 37% 12% 1	3891
	21st to end	Night	39% 4 13% 33% 11%	4467
November	1st to 10th	Night	54% 7% 13% 17% 7% 1	2557
	11th to 20th	Night	54% 7% 18% 14% 5%	2660
	21st to end	Night	51% 7% 19% 19% 4	2816
December	1st to 10th	Night	59% 5% 15% 16% 5%	2850
	11th to 20th	Night	60% 7% 13% 15% 5% 1	3556
	21st to end	Night	36% 7% 13% 23% 16% 5%	5562

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	11% 8% 37% 23% 17% 4	180
	11th to 20th	Day	9% 9% 33% 34% 13% 2	264
	21st to end	Day	13% 9% 35% 30% 12% 1	297
February	1st to 10th	Day	15% 8% 38% 28% 10% 1	270
	11th to 20th	Day	13% 9% 33% 29% 14% 2	270
	21st to end	Day	8% 5% 33% 38% 16% 1	225
March	1st to 10th	Day	13% 7% 37% 29% 11% 3	270
	11th to 20th	Day	11% 11% 38% 28% 9% 4	354
	21st to end	Day	13% 13% 31% 27% 14% 2	506
April	1st to 10th	Day	9% 16% 37% 28% 8% 2	460
	11th to 20th	Day	19% 13% 31% 25% 10% 1	480
	21st to end	Day	16% 10% 29% 29% 15% 1	650
May	1st to 10th	Day	14% 8% 30% 29% 18% 2	653
	11th to 20th	Day	13% 9% 26% 30% 15% 7%	675
	21st to end	Day	17% 9% 25% 27% 18% 5%	734
June	1st to 10th	Day	15% 12% 29% 24% 16% 4	680
	11th to 20th	Day	19% 13% 31% 22% 13% 2	680
	21st to end	Day	11% 8% 26% 30% 22% 3	680
July	1st to 10th	Day	7% 6% 23% 38% 21% 6%	671
	11th to 20th	Day	7% 8% 29% 30% 20% 6%	668
	21st to end	Day	6% 8% 27% 31% 21% 9%	739
August	1st to 10th	Day	9% 6% 23% 37% 19% 6%	676
	11th to 20th	Day	9% 4 22% 34% 24% 6%	665
	21st to end	Day	10% 9% 23% 33% 21% 4	546
September	1st to 10th	Day	13% 12% 31% 28% 14% 2	490
	11th to 20th	Day	17% 9% 30% 28% 14% 1	473
	21st to end	Day	14% 9% 34% 29% 11% 2	300
October	1st to 10th	Day	18% 9% 30% 24% 15% 3	300
	11th to 20th	Day	11% 12% 36% 27% 13% 2	300
	21st to end	Day	14% 13% 38% 25% 7% 2	330
November	1st to 10th	Day	20% 8% 32% 26% 13% 2	279
	11th to 20th	Day	12% 9% 42% 30% 6%	270
	21st to end	Day	12% 10% 37% 30% 10% 1	270
December	1st to 10th	Day	12% 8% 34% 33% 11% 2	270
	11th to 20th	Day	12% 9% 49% 22% 8%	255
	21st to end	Day	12% 7% 35% 33% 11% 3	198
January	1st to 10th	Night	8% 11% 35% 33% 11% 2	950
	11th to 20th	Night	13% 10% 33% 36% 7% 1	950
	21st to end	Night	10% 11% 38% 31% 10% 1	1045
February	1st to 10th	Night	12% 6% 34% 34% 12% 2	926
	11th to 20th	Night	9% 7% 35% 37% 10% 2	744
	21st to end	Night	6% 6% 26% 39% 20% 4	628
March	1st to 10th	Night	12% 7% 35% 33% 12% 1	760
	11th to 20th	Night	10% 8% 35% 33% 13% 1	760
	21st to end	Night	13% 6% 30% 36% 13% 1	656
April	1st to 10th	Night	11% 9% 33% 34% 12% 1	570
	11th to 20th	Night	18% 9% 32% 33% 7% 1	563
	21st to end	Night	17% 8% 32% 36% 7%	570
May	1st to 10th	Night	15% 7% 26% 37% 13% 1	570
	11th to 20th	Night	13% 7% 29% 34% 16% 1	561
	21st to end	Night	18% 5% 27% 33% 15% 2	617
June	1st to 10th	Night	13% 5% 29% 35% 16% 1	475
	11th to 20th	Night	20% 6% 26% 38% 10% 1	380
	21st to end	Night	13% 6% 23% 41% 17% 1	380
July	1st to 10th	Night	9% 2 28% 39% 21% 2	370
	11th to 20th	Night	7% 4 27% 44% 17%	462
	21st to end	Night	6% 4 26% 42% 20% 3	624
August	1st to 10th	Night	8% 4 26% 40% 20% 2	567
	11th to 20th	Night	6% 4 20% 41% 26% 2	564
	21st to end	Night	10% 5% 27% 39% 19% 1	627
September	1st to 10th	Night	10% 6% 26% 37% 19% 2	570
	11th to 20th	Night	14% 6% 25% 39% 15% 1	570
	21st to end	Night	11% 7% 31% 40% 10% 1	589
October	1st to 10th	Night	19% 6% 25% 35% 15% 1	760
	11th to 20th	Night	13% 7% 29% 38% 13% 1	822
	21st to end	Night	17% 9% 31% 34% 9% 1	1045
November	1st to 10th	Night	21% 8% 33% 30% 8% 1	943
	11th to 20th	Night	14% 10% 33% 31% 10% 1	950
	21st to end	Night	13% 9% 38% 32% 6% 1	950
December	1st to 10th	Night	12% 7% 36% 31% 12% 3	950
	11th to 20th	Night	12% 12% 33% 32% 10% 1	950
	21st to end	Night	12% 5% 34% 34% 13% 2	1045

Page generated at 2024-11-01 20:47:38. Version ac07

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